NCERT Exemplar: Coordinate Geometry - 1

# NCERT Exemplar: Coordinate Geometry - 1 | Mathematics (Maths) Class 10 PDF Download

## EXERCISE 7.1

Choose the correct answer from the given four options:
Q1: The distance of the point P (2, 3) from the x-axis is
(a) 2

(b) 3
(c) 1
(d) 5

Let us mark the point P (2, 3) in the Cartesian plane.
The shortest distance between the coordinate (2, 3) and the x – axis is a straight line to the point (2, 0).
We are said to find the shortest distance from (x - axis). So the point is (2, 0).

To find the distance, we can use the distance formula.

Distance formula

Here, (x1,y1)=(2,0), (x2,y2)=(2,3)

Thus the shortest distance of the point P (2, 3) to the x – axis is 3 units.

∴  Option (b) is the correct answer.

Q2: The distance between the points A (0, 6) and B (0, –2) is
(a) 6

(b) 8
(c) 4
(d) 2

We know that the formula to find the distance between two points A(x₁, y₁) and B(x₂, y₂) is

It is given that
We have to find the distance between the points A (0, 6) and B (0, –2)
Substituting these values in the equation we get

So we get
Distance between A and B = √64
Distance between A and B = 8 units
Therefore, the distance between the points A and B is 8 units.

Q3: The distance of the point P (–6, 8) from the origin is
(a) 8

(b) 2√7
(c) 10
(d) 6

We know that the formula to find the distance between two points P(x₁, y₁) and Q(x₂, y₂) is

It is given that

We have to find the distance of the point P (-6, 8) from origin i.e. (0, 0)

Substituting these values in the equation we get

So we get

Distance of point P = √(36 + 64) = √100 = 10

Distance of point P = 10 units

Therefore, the distance of the point P (–6, 8) from the origin is 10 units.

Q4: Find distance between the points (0, 5) and (- 5, 0).
(a) 5
(b) 5√2
(c) 2√5
(d) 10

Here

Q5: AOBC is a rectangle whose three vertices are A (0, 3), O (0, 0) and B (5, 0). Find the length of its diagonal.
(a) 5
(b) 3
(c) √34
(d) 4

It is given that
AOBC is a rectangle whose three vertices are vertices A (0, 3), O (0, 0) and B (5, 0)

Length of diagonal AB is the distance between the points (0,3) and (5,0)
We know that the formula to find the distance between two points P(x₁, y₁) and Q(x₂, y₂) is

Distance between the points (0,3) and (5,0) can be found by

So we get
Distance between the points = √(25 + 9) = √34
Distance between the points = √34 units
Therefore, the length of its diagonal is √34 units.

Q6: The perimeter of a triangle with vertices (0, 4), (0, 0) and (3, 0) is
(a) 5
(b) 12
(c) 11
(d) 7 + √5

First find length of each sides of ∆
Let A( 4 , 0) B(0, 0) and C (0 , 3) be the vertices of the triangle.
Using distance formula we have

Clearly adding AB + BC + CA = perimeter of ∆

⇒ Perimeter of ∆ ABC = 3 + 4 + 5= 12 units

Q7: The area of a triangle with vertices A (3, 0), B (7, 0) and C (8, 4) is
(a) 14
(b) 28
(c) 8
(d) 6

The vertices of the triangle are
A (3, 0), B (7, 0) and C (8, 4)
The formula to find the area of a triangle is
Area = 1/2 [x1(y2 - y3) + x2(y3 - y1) + x3(y1 - y2)]
Substituting the values
Area = 1/2 [3(0 - 4) + 7(4 - 0) + 8(0 - 0)]
By further calculation
Area = 1/2 [3(-4) + 7(4) + 8(0)]

Area = 1/2 [-12 + 28]

So we get

Area = 1/2 [16]

Area = 8 sq. units

Therefore, the area of a triangle is 8 sq. units.

Q8: The points (–4, 0), (4, 0), (0, 3) are the vertices of a
(a) right triangle
(b) isosceles triangle
(c) equilateral triangle
(d) scalene triangle

Consider A(-4, 0), B(4, 0), C(0, 3) as the vertices given

We know that the formula to find the distance between two points (x₁, y₁) and (x₂, y₂) is

Now distance between A and B

Distance between B and C

Distance between A and C

As BC = AC the triangle is isosceles

Therefore, the points are the vertices of an isosceles triangle.

Q9: The point which divides the line segment joining the points (7, –6) and (3, 4) in ratio 1 : 2 internally lies in the

We know that

The coordinates of the point P which divides the line segment joining the points A(x1, y1) and B(x2, y2) internally in the ratio m1: m2 are

It is given that

(x1, y1) = (7, -6)

(x2, y2) = (3, 4)

m1 = 1

m2 = 2

Substituting the values in the section formula

As the x coordinate is positive and y coordinate is negative.
The point lies in the IV quadrant.

Q10: The point which lies on the perpendicular bisector of the line segment joining the points A (–2, –5) and B (2, 5) is
(a) (0, 0)
(b) (0, 2)
(c) (2, 0)

(d) (–2, 0)

We know that
The coordinates of the mid-point of the line segment joining the point P (x1, y1) and Q (x2, y2) are [(x1 + x2)/2, (y1 + y2)/2]
The points given are A (-2, -5) and B (2, 5)
Now by substituting the values in the formula
= [(-2 + 2)/2, (-5 + 5)/2]
= (0/2, 0/2)
= (0, 0)
Therefore, the point which lies on the perpendicular is (0, 0).

Q11: The fourth vertex D of a parallelogram ABCD whose three vertices are A (–2, 3), B (6, 7) and C (8, 3) is
(a) (0, 1)
(b) (0, –1)
(c) (–1, 0)
(d) (1, 0)

Consider the fourth vertex as D = (x, y)
As the diagonals of a parallelogram bisect each other, the midpoint of AC is the same as the midpoint of BD.
We know that
The coordinates of the mid-point of the line segment joining the point are
[(x1 + x2)/2, (y1 + y2)/2]
As the midpoint of AC = Midpoint of BD
[(-2 + 8)/2, (3 + 3)/2] = [(6 + x)/2, (7 + y)/2]
By further calculation

[6/2, 6/2] = [(6 + x)/2, (7 + y)/2]

Now we get

6 + x = 6

x = 6 - 6 = 0

And 7 + y = 6

y = 6 - 7 = -1

Therefore, the fourth vertex D is (0, -1).

Q12: If the point P (2, 1) lies on the line segment joining points A (4, 2) and B (8, 4), then
(a) AP = 1/3AB
(b) AP = PB
(c) PB = 1/3AB
(d) AP = 1/2AB

We know that

The coordinates of the point (x, y) which divides the line segment joining the points (x1, y1) and (x2, y2) internally in the ratio m₁: m₂ are

Consider P to divide AB in the ratio k:1

Let us substitute the values (x1, y1) = (4, 2) and (x2, y2) = (8, 4)

It is given that P = (2, 1)

Let us compare the x coordinates
(8k + 4)/ (k + 1) = 2
By cross multiplication
8k + 4 = 2k + 2
6k = -2
Divide both sides by -2
k = -1/3
As k value is negative, P divides AB in the ratio 1:3 externally
AP/PB = 1/3
AP = 1/2 AB
Therefore, the line segment joining points A (4, 2) and B (8, 4), then AP = 1/2 AB.

Q13: If P a/3, 4 is the mid-point of the line segment joining the points Q (– 6, 5) and R (– 2, 3), then the value of a is
(a) -4
(b) -12
(c) 12
(d) -6

It is given that
P is the mid-point of the line segment QR
Px = a/3 = (-6 - 2)/2
By cross multiplication we get
2a = -24
Dividing both sides by 2
a = -12
Therefore, the value of a is -12.

Q14: The perpendicular bisector of the line segment joining the points A (1, 5) and B (4, 6) cuts the y-axis at
(a) (0, 13)
(b) (0, –13)
(c) (0, 12)
(d) (13, 0)

The points given are

A(x₁, y₁) = (1, 5)

B(x₂, y₂) = (4, 6)

Perpendicular bisector of AB will pass through the mid-point of AB

Perpendicular bisector of AB will meet the Y axis at P(0, y)

AP = BP

We know that

The distance between two points P(x₁, y₁) and Q(x₂, y₂) is

Let us apply the distance formula

AP2 = BP2

(x1 - 0)2 + (y1 - y)2 = (x2 - 0)2 + (x2₂ - y)2
Substituting the values
(1- 0)2 + (5 - y)2 = (4 - 0)2 + (6 - y)2
Let us expand using (a - b)2 = a2 + b2 - 2ab
1 + 25 + y2 - 10y = 16 + 36 + y2- 12y
By further calculation
26 + y2 - 10y = 52 + y2 - 12y
So we get
y2 - 10y - y2 + 12y + 26 - 52 = 0
2y - 26 = 0
2y = 26
Divide both sides by 2
y = 13
Therefore, the perpendicular bisector of the line segment is (0, 13).

Q15: The coordinates of the point which is equidistant from the three vertices of the ∆ AOB as shown in the figure is

(a) (x, y)
(b) (y, x)
(c) x/2, y/2
(d) y/2, x/2

Consider the coordinate of the point which is equidistant from the three vertices O (0, 0), A (0,
2y) and B (2x, 0) as P (h, k)
Here PO = PA = PB

PO2 = PA2 = PB2   --- (1)

Now we get
h2 + k2 = h2 + (k - 2y)2 = (h - 2x)2 + k2    --- (1)
Let us consider the first two equation
h2 + k2 = h2 + (k - 2y)2
k2 = k2 + 4y2 - 4yk
Taking out the common terms
4y(y - k) = 0
y = k where y ≠ 0
Considering the first and third equation

h2 + k2 = (h - 2x)2 + k2
h2 = h2 + 4x2 - 4xh
Taking out the common terms
4x(x - h) = 0
x = h where x ≠ 0
So the required points are (h, k) = (x, y)
Therefore, the coordinates of the point are (x, y).

Q16: A circle drawn with origin as the centre passes through (13/2,0).  The point which does not lie in the interior of the circle is
(a) -3/4, 1
(b) 2.7/3
(c) 5,-1/3
(d) -6,5/2

It is given that

A circle is drawn with origin as centre (0, 0) passes through (13/2, 0)

We know that

Radius of the circle = Distance between the two points

A point lies inside, on or outside the circle if the distance of the point from the centre of the circle is less than, equal to or greater than the radius of the circle.

Let us now check the options one by one

a. The distance between (0, 0) and (-3/4, 1)

(-3/4, 1) lies in the interior of the circle.

b. The distance between (0, 0) and (2, 7/3)

(2, 7/3) lies in the interior of the circle.

c. The distance between (0, 0) and (5, -1/2)

(5, -1/2) lies in the interior of the circle.
d. The distance between (0, 0) and (-6, 5/2)

(-6, 5/2) lies on the circle.

Therefore, the point (-6, 5/2) does not lie in the interior of the circle.

Q17: A line intersects the y-axis and x-axis at the points P and Q, respectively. If

(2, –5) is the mid-point of PQ, then the coordinates of P and Q are, respectively
(a) (0, – 5) and (2, 0)
(b) (0, 10) and (– 4, 0)
(c) (0, 4) and (– 10, 0)
(d) (0, – 10) and (4, 0)

We know that
The coordinates of the mid-point of the line segment joining the point are
[(x1 + x2)/2, (y1 + y2)/2]
Consider the coordinates of P as (x, y) and Q as (x2, y2)
The midpoint of PQ = (2, -5)
Using the midpoint formula
x = (x1 + x2)/2 and y = (y1 + y2)/2
2 = (x1 + x2)/2 and -5 = (y1 + y2)/2
By cross multiplication
x1 + x2 = 4
y1 + y2 = -10
As the line PQ intersects the Y-axis at P
x1 = 0
In the same way, y2 = 0
x2 = 4 and y1 = -10
So the coordinates of P is (0, -10) and Q is (4, 0).
Therefore, the coordinates of P and Q are (0, -10) and (4, 0).

Q18: The area of a triangle with vertices (a, b + c), (b, c + a) and (c, a + b) is
(a) (a + b + c)2
(b) 0
(c) a + b + c
(d) abc

Consider the vertices of a triangle as

A = (x₁, y₁) = (a, b + c)

B = (x₂, y₂) = (b, c + a)

C = (x₃, y₃) = (c, a + b)

We know that
Area of triangle ABC = Δ = 1/2 [x1(y2 - y3) + x2(y3 - y1) + x3(y1 - y2)]
Let us substitute the values
Δ = 1/2 [a (c + a - a - b) + b (a + b - b - c) + c (b + c - c - a)]
By further simplification
Δ = 1/2 [a (c - b) + b (a - c) + c (b - a)]
Δ = 1/2 [ac - ab + ab - bc + bc - ac]
So we get
Δ = 1/2 [0]
Δ = 0
Therefore, the area of the triangle is 0.

Q19: If the distance between the points (4, p) and (1, 0) is 5, then the value of p is
(a) 4 only
(b) ± 4
(c) – 4 only
(d) 0

We know that
The distance between two points P(x1, y1) and Q(x2, y2) is

The points given are (4, p) and (1, 0)
Let us apply the distance formula

By squaring on both sides
25 = (4 - 1)2 + p2
25 = 32 + p2
By further calculation
25 = 9 + p2
p2 = 25 - 9 = 16
So we get
p = ±4
Therefore, the value of p is ±4.

Q20: If the points A (1, 2), O (0, 0) and C (a, b) are collinear, then

(a) a = b
(b) a = 2b
(c) 2a = b
(d) a = –b

As the given points are collinear, it does not form a triangle

It means that the area of triangle is zero

We know that

Area of triangle with vertices (x1, y1), (x2, y2) and (x3, y3) is

The points given are

(x1, y1) = (1, 2)

(x2, y2) = (0, 0)

(x3, y3) = (a, b)
By substituting these values

So we get
-b + 2a = 0
2a = b
Therefore, if the points are collinear, then 2a = b.

## EXERCISE 7.2

Q1: State whether the following statements are true or false. Justify your answer.
ΔABC with vertices A(-2, 0), B(0, 2) and C(2, 0) is similar to ΔDEF with vertices D(-4, 0), F(4, 0) and E(0, 4).

Given, vertices of ∆ ABC are A(-2, 0) B(2, 0) and C(0, 2)
Vertices of ∆ DEF are D(-4, 0) E(4, 0) and F(0, 4)
We have to check if the triangles ABC and DEF are similar.
By the property of similarity,
The corresponding sides must be in proportion.
So, the side length of each triangle is calculated using the distance formula and verified whether it is proportional.
The distance between two points P (x₁ , y₁) and Q (x₂ , y₂) is
√[(x₂ - x₁)2 + (y2 - y₁)2]
The side length of ∆ ABC are
AB = √[(2 - (-2))2 + (0 - 0)2] = √(4)2 = √16 = 4
BC = √[(0 - 2)2 + (2 - 0)2] = √[(2)2 + (2)2] = √(4 + 4) = 2√2
AC = √[(0 - (-2))2 + (2 - 0)2] = √[4 + 4] = 2√2
The side length of ∆ DEF are
DE = √[(4 - (-4))+ (0 - 0)2] = √(8)2 = 8
EF = √[(0 - 4)2 + (4 - 0)2] = √[(-4)2 + (4)2] = √(16 + 16) = √32 = 4√2
DF = √[(0 - (-4))2 + (4 - 0)2] = √(16 + 16) = √32 = 4√2
Now, AB/DE = BC/EF = AC/DF
4/8 = 2√2/4√2 = 2√2/4√2 = 1/2
So, the corresponding sides are in proportion.
Therefore, ∆ ABC ⩬ ∆ DEF

Q2: State whether the following statements are true or false. Justify your answer.
Point P (– 4, 2) lies on the line segment joining the points A (– 4, 6) and B (– 4, – 6).

Given, line segment joining the points A(-4, 6) and B(-4, -6)
We have to determine if the point P(-4, 2) lies on the line segment.
A line segment joining the point Q (x1 , y1) is
y - y1 = m(x - x1)
Where, m is the slope.
The slope of the line joining two points P (x1 , y1) and Q (x2 , y2) is is given by m = (y2 - y1)/(x2 - x1)

Here, A(-4, 6) and B(-4, -6
Slope, m = -6 - 6/(-4 - (-4) = -12/0 = ∞
Now, the line segment is y - 6 = (12/0)(x - (-4))
(y - 6)(0) = -12(x + 4)
0 = -12(x + 4

x + 4 = 0 -------------- (1)
If the point P(-4, 2) lies on the line segment then it has to satisfy the equation (1),

Put x = -4 in (1)
-4 + 4 = 0
0 = 0
Therefore, the point P lies on the line AB.

Q3: State whether the following statements are true or false. Justify your answer.
The points (0, 5), (0, –9) and (3, 6) are collinear.

Given, the points are (0, 5) (0, -9) and (3, 6).
We have to check if the points are collinear.
The area of a triangle with vertices A (x1 , y1) , B (x2 , y2) and C (x3 , y3) is 1/2[x1(y2 - y3) + x2(y3- y1) + x3(y1 - y2)]
To check for the points to be collinear, the area of the triangle must be zero.
Here, (x1 , y1) = (0, 5), (x2 , y2) = (0, -9) and (x3 , y3) = (3, 6)
Area of triangle = 1/2[0(-9 - 6) + 0(6 - (-9)) + 3(5 - (-9))
= 1/2[0 + 0 + 3(5 + 9)]
= 1/2[3(14)]
= 3(7)
= 21
Area of the triangle ≠ 0
Therefore, the given points are not collinear.

Q4: State whether the following statements are true or false. Justify your answer.
Point P (0, 2) is the point of intersection of y–axis and perpendicular bisector of line

segment joining the points A (–1, 1) and B (3, 3).

Given, a line segment joining the points A(-1, 1) and B(3, 3)
We have to determine if the point P(0, 2) is the point of intersection of the y-axis and perpendicular bisector of the given line segment.
We know that any point lying on the perpendicular bisector of the line segment joining two points is equidistant from the two points.
The perpendicular bisector joining the two points are A(-1, 1) and B(3, 3)
To check if the point P lies on the perpendicular bisector, then distance between PA must be equal to distance between PB i.e., PA = PB
The distance between two points P (x1 , y1) and Q (x2 , y2) is

√[(x2 - x1)2+(y2 - y1)2]
To find distance between P(0, 2) and A(-1, 1)
PA = √[(-1 - 0)2+(1 - 2)2] = √[(-1)2+(-1)2] = √(1+1) = √2
To find distance between P(0, 2) and B(3, 3)
PB = √[(3 - 0)2+(3 - 2)2] = √[(3)2+(1)2] = √(9+1) = √10
It is clear that PA ≠ PB
Therefore, point P(0, 2) does not lie on the perpendicular bisector of the line segment.

Q5: State whether the following statements are true or false. Justify your answer.
Points A (3, 1), B (12, –2) and C (0, 2) cannot be the vertices of a triangle.

Given, the points are A(3, 1) B(12 , -2) and C(0, 2)
We have to determine if the given points represent the vertices of a triangle.
We know that,
A triangle can be formed from any three line segments provided the sum of the lengths of any two of the segments is greater than the length of the third.
The distance between two points P (x₁ , y₁) and Q (x₂ , y₂) is
√[(x2 - x1)2+(y2 - y1)2]
The length of AB = √[(12 - 3)2+(-2 - 1)2]
= √[(9)²+(-3)²]
= √(81 + 9)
= √90
AB = 3√10
The length of BC = √[(0 -12)2+(2 - (-2))2]
= √[(-12)2+(4)2]
= √(144 + 16)
= √160
BC = 4√10
The length of AC = √[(0 - 3)2+(2 - 1)2]
= √[(-3)2+(1)2]
= √(9 + 1)
AC = √10
Now, sum of the two sides of a triangle = AB + AC
= 3√10 + √10
= 4√10
= BC
So, AB + AC ⪈ BC
Therefore, the given points do not form the vertices of a triangle.

Q6: State whether the following statements are true or false. Justify your answer.
Points A (4, 3), B (6, 4), C (5, –6) and D (–3, 5) are the vertices of a parallelogram.

Given, the points are A(4, 3) B(6, 4) C(5, -6) and D(-3, 5)
We have to determine if the given points are the vertices of a parallelogram.
By the property of parallelogram,
The opposite sides of a parallelogram are equal.
The distance between two points P (x₁ , y₁) and Q (x₂ , y₂) is
√[(x2 - x1)2+(y2 - y1)2]
AB = √[(6 - 4)2+(4 - 3)2]
= √[(2)2+(1)2]
= √(4 + 1)
AB = √5
BC = √[(5 - 6)2+(-6 - 4)2]
= √[(-1)2+(-10)2]
= √(1 + 100)
BC = √101
CD = √[(-3 - 5)2+(5 - (-6))2]
= √[(-8)2+(11)2]
= √(64 + 121)
CD = √185
AD = √[(-3 - 4)2+(5 - 3)2]
= √[(-7)2+(2)2]
= √(49 + 4)
It is clear that AB ≠ CD and BC ≠ AD
The opposite sides are not equal.
Therefore, the given points are not the vertices of a parallelogram.

Q7: State whether the following statements are true or false. Justify your answer.
A circle has its centre at the origin and a point P (5, 0) lies on it. The point

Q (6, 8) lies outside the circle.
Given, the centre of the circle is at the origin.
Point P(5, 0) lies on the circle.
We have to determine if the point Q(6, 8) lies outside the circle.
We know that, if the distance of any point from the centre is less than the radius, then the point is inside the circle equal to the radius, then the point is on the circle.
more than the radius, then the point is outside the circle.
To find the radius of the circle,
Radius of the circle is equal to the distance between the origin and the point P(5, 0)
The distance between two points P (x1 , y1) and Q (x2 , y2) is
√[(x2 - x1)2+(y2 - y1)2]
So, OP = radius of the circle = √[(5 - 0)2+(0 - 0)2]
= √[(5)2+0]
= √25
OP = 5
Distance between the origin and Q(6, 8) = √[(6 - 0)²+(8 - 0)²]
= √[(6)²+(8)²]
= √(36 + 64)
= √100
OQ = 10
We observe that OQ > OP
The distance of the point OQ is greater than the radius of the circle.
Therefore, the point Q lies outside the circle.

Q8: State whether the following statements are true or false. Justify your answer.
The point A (2, 7) lies on the perpendicular bisector of line segment joining the points P (6, 5) and Q (0, – 4).

Given, the line segment joining the points P(6, 5) and Q(0, -4)
We have to determine if the point A(2, 7) lies on the perpendicular bisector of the line segment.
We know that any point lying on the perpendicular bisector of the line segment joining two points is equidistant from the two points.
The perpendicular bisectors joining the two points are P(6, 5) and Q(0, -4)
To check if the point A lies on the perpendicular bisector, then distance between PA must be equal to distance between QA i.e., PA = QA
The distance between two points P (x1 , y1) and Q (x2 , y2) is
√[(x2 - x1)2 + (y2 - y1)2]
The distance between the points P(6, 5) and A(2, 7) = √[(2 - 6)2 + (7 - 5)2]
= √[(-4)2 + (2)2]
= √(16 + 4)
= √20
= 2√5
The distance between the points Q(0, -4) and A(2, 7) = √[(2 - 0)2 + (7 - (-4))2]
= √[(2)2 + (11)2]
= √(4 + 121)
= √125
= 5√5
PA ≠ QA
Therefore, point A(2, 7) does not lie on the perpendicular bisector of the line segment joining the given points.

Q9: State whether the following statements are true or false. Justify your answer.
Point P (5, –3) is one of the two points of trisection of the line segment joining the points A (7, – 2) and B (1, – 5).

Given, the line segment joining the points A(7, -2) and B(1, -5)
We have to check if the P(5, -3) is one of the two points of trisection of the line segment joining the given points.
By section formula,
The coordinates of the point P(x, y) which divides the line segment joining the points A (x₁ , y₁) and B (x2 , y2) internally in the ratio k : 1 are [(kx2 + x1)/k + 1 , (ky2 + y1)/k + 1]
P(5, -3) divides the line segment A(7, -2) and B(1, -5) internally in the ratio k:1
So, (5, -3) = [k(1) + (7))/k + 1 , (k(-5) + (-2))/k + 1]
(5, -3) = [k + 7/k + 1, -5k - 2/k + 1]
Now, k + 7/k + 1 = 5
k + 7 = 5(k + 1)
k + 7 = 5k + 5
By grouping,
5k - k = 7 - 5
4k = 2
k = 2/4
k = 1/2
The point P(5, -3) divides the line segment AB in the ratio 1:2.
Therefore, point P is the point of trisection of AB.

Q10: State whether the following statements are true or false. Justify your answer. Points A (–6, 10), B (–4, 6) and C (3, –8) are collinear such that AB =2/9 AC .

Given, the points are A(-6, 10) B(-4, 6) and C(3, -8)

We have to check if the points are collinear and prove that AB = 2/9 AC.

The area of a triangle with vertices A (x1 , y1) , B (x2 , y2) and C (x3 , y3) is

1/2[x1(y2 - y3) + x2(y3 - y1) + x3(y1 - y2)]

To check for the points to be collinear, the area of the triangle must be zero.

Here, (x1 , y1) = (-6, 10), (x2 , y2) = (-4, 6) and (x3 , y3) = (3, -8)

Area of triangle = 1/2[-6(6 - (-8)) + -4(-8 - 10) + 3(10 - 6)

= 1/2[-6(14) + -4(-18) + 3(4)]

= 1/2[-84 + 72 + 12]

= 1/2[-84 + 84]

= 0

Area of the triangle = 0

Therefore, the points are collinear.

The distance between two points P (x1 , y1) and Q (x₂ , y₂) is

√[(x₂ - x₁)² + (y₂ - y1)²]

The distance between the points A(-6, 10) and B(-4, 6)

AB = √[(-4 - (-6))² + (6 - 10)²]

= √[(2)² + (-4)²]

= √(4 + 16)

= √20

= 2√5

The distance between the points A(-6, 10) and C(3, -8)

AC = √[(3 - (-6))² + (-8 - 10)²]

= √[(9)² + (-18)²]

= √(81 + 324)

= √405

= 9√5

Now, 2/9 AC = 2/9(9√5) = 2√5 = AB

Therefore, AB = 2/9 AC

Q11: State whether the following statements are true or false. Justify your answer. The point P (–2, 4) lies on a circle of radius 6 and centre C (3, 5).

Given, the circle with radius 6 and centre C(3, 5)
We have to determine if the point P(-2, 4) lies on the circle.
We know that, if the distance of any point from the centre is

• less than the radius, then the point is inside the circle
• equal to the radius, then the point is on the circle.
• more than the radius, then the point is outside the circle.

The distance between two points P (x1 , y1) and Q (x2 , y2) is
√[(x2 - x1)2 + (y2 - y1)2]
The distance between P(-2, 4) and C(3, 5)
PC = √[(3 - (-2))2 + (5 - 4)2]
= √[(5)2 + (1)2]
= √(25 + 1)
PC = √26
It is clear that PC < Radius of the circle
The distance between the point P from the centre is less than the radius of the circle.
Therefore, the point lies inside the circle.

Q12: State whether the following statements are true or false. Justify your answer. The points A (–1, –2), B (4, 3), C (2, 5) and D (–3, 0) in that order form a rectangle.

ABCD will form a rectangle if

(i) It is a parallelogram . (ii) diagonals are equal.

For parallelogram : Diagonals bisect each other.

i.e., Mid point of AC = Mid point of BD is

Hence , ABCD is a parallelogram.

Now , Diagonal

⇒ AC =  √58  units
and Diagonal

∴ Diagonals AC = Diagonal BD
Hence , ABCD is a rectangle.

The document NCERT Exemplar: Coordinate Geometry - 1 | Mathematics (Maths) Class 10 is a part of the Class 10 Course Mathematics (Maths) Class 10.
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## Mathematics (Maths) Class 10

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## FAQs on NCERT Exemplar: Coordinate Geometry - 1 - Mathematics (Maths) Class 10

 1. What is coordinate geometry and how is it used in mathematics?
Ans. Coordinate geometry is a branch of mathematics that deals with the study of geometric figures using coordinates. In this system, points on a plane are represented by ordered pairs of numbers called coordinates. These coordinates help determine the position, distance, and relationships between points, lines, and shapes. Coordinate geometry is widely used in various fields, including physics, engineering, computer science, and navigation.
 2. How do you find the distance between two points in coordinate geometry?
Ans. To find the distance between two points (x1, y1) and (x2, y2) in coordinate geometry, we can use the distance formula. The distance formula is derived from the Pythagorean theorem and is given by: Distance = √((x2 - x1)^2 + (y2 - y1)^2) By substituting the coordinates of the two points into this formula, we can calculate the distance between them.
 3. What is the midpoint formula in coordinate geometry?
Ans. The midpoint formula is used to find the coordinates of the midpoint between two given points in coordinate geometry. The coordinates of the midpoint (x, y) can be calculated using the following formula: x = (x1 + x2) / 2 y = (y1 + y2) / 2 Here, (x1, y1) and (x2, y2) are the coordinates of the given points. By substituting these values into the formula, we can determine the midpoint of the line segment connecting the two points.
 4. How can we determine if three points are collinear in coordinate geometry?
Ans. In coordinate geometry, collinear points are points that lie on the same straight line. To determine if three points (x1, y1), (x2, y2), and (x3, y3) are collinear, we can use the slope formula. First, calculate the slopes between the first two points and the second two points: Slope1 = (y2 - y1) / (x2 - x1) Slope2 = (y3 - y2) / (x3 - x2) If the slopes are equal, then the three points are collinear. However, if the slopes are not equal, the points do not lie on the same line.
 5. How can we find the equation of a straight line in coordinate geometry?
Ans. The equation of a straight line in coordinate geometry can be found using different methods depending on the given information. 1. Slope-intercept form: If we know the slope (m) of the line and the y-intercept (b), the equation can be written as y = mx + b. 2. Point-slope form: If we know a point (x1, y1) on the line and the slope (m), the equation can be written as y - y1 = m(x - x1). 3. Two-point form: If we know two points (x1, y1) and (x2, y2) on the line, the equation can be written as (y - y1) / (y2 - y1) = (x - x1) / (x2 - x1). By using any of these forms and substituting the given values, we can determine the equation of the straight line.

## Mathematics (Maths) Class 10

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