Using mid-point formula, we have
⇒x1=−1, y1=2
Coordinates of P = (−1, 2)
Also,
Coordinates of R = (1, −4)
So, P(−1, 2), Q(3, 2) and R(1, −4) are the vertices of ∆PQR.
=12 square units
Hence, the area of the triangle is 12 square units.
Area of the quadrilateral PQRS = Area of ∆PQR + Area of ∆PRS
=1/2|−5[−6−(−3)]+(−4)[−3−(−3)]+2[−3−(−6)]|
=1/2|15+0+6|
= 21/2 square units
= 35/2 square units
∴ Area of the quadrilateral PQRS = square units
Hence, the area of the given quarilateral is 28 square units.
Area of the quadrilateral ABCD = Area of ∆ABC + Area of ∆ACD
=1/2
|−3[−7−(−8)]+(−2)(−8−5)+1[5−(−7)]|
=1/2|−3+26+12|
=35/2 square units
=1/2|−3(−8−3)+1(3−5)+6[5−(−8)]|
=1/2|33−2+78|
= 109/2 square units
∴ Area of the quadrilateral ABCD = 72 square units
Hence, the area of the given quadrilateral is 72 square units.
If three points are collinear the area encompassed by them is equal to 0.
The three given points are A(a, 1), B(1, −1) and C(11, 4). It is also said that they are collinear and hence the area enclosed by them should be 0.
Δ=1/2 |(x1y2+x2y3+x3y1)−(x2y1+x3y2+x1y3)|
0=1/2 |(a×−1+1×4+11×1)−(1×1+11×−1+a×4)|
0=1/2 | (−a+4+11)−(1−11+4a)|
0=1/2|(−a+15)−(−10+4a)|
0=1/2|−a+15+10−4a|
0=1/2|−5a+25|
0=−5a+25
5a=25
a=5
Hence the value of ‘a’ for which the given points are collinear is.
Δ=1/2|(x1y2+x2y3+x3y1)−(x2y1+x3y2+x1y3)|
If three points are collinear the area encompassed by them is equal to 0.
The three given points are, and. If they are collinear then the area enclosed by them should be 0.
Δ=1/2|(ab1+a1(b−b1)+(a−a1)b)−(a1b+(a−a1)b1+a(b−b1))|
0=1/2|(ab1+a1b−a1b1+ab−a1b)−(a1b+ab1−a1b1+ab−ab1)|
0=1/2|ab1+a1b−a1b1+ab−a1b−a1b−ab1+a1b1−ab+ab1|
0=ab1−a1b
ab1=a1b
Hence we have proved that for the given conditions to be satisfied we need to have.
⇒1/2|x1(y2−y3)+x2(y3−y1)+x3(y1−y2)|=15⇒1/2|1(p−7)+4[7−(−3)]+(−9)(−3−p)|=15⇒1/2|p−7+40+27+9p|=15⇒|10p+60|=30
⇒10p+60=30 or 10p+60=−30
⇒10p=−30 or 10p=−90
⇒p=−3 or p=−9
Hence, the value of p is −3 or −9.
That is,
Thus, the result is proved.
Δ=1/2|(x1y2+x2y3+x3y1)−(x2y1+x3y2+x1y3)|
If three points are collinear the area encompassed by them is equal to 0.
The three given points are A(k, 3), B(6, −2) and C(−3, 4). It is also said that they are collinear and hence the area enclosed by them should be 0.
Δ=1/2|(k(−2)+6×4+(−3)×3)−(6×3+(−3)(−2)+k×4)| 0=1/2|(−2k+24−9)−(18+6+4k)| 0=1/2|−2k+15−24−4k| 0=1/2|−6k−9| 0=−6k−9 k=−9/6 =−3/2
Hence the value of ‘k’ for which the given points are collinear is.
Δ=1/2|(x1y2+x2y3+x3y1)−(x2y1+x3y2+x1y3)|
If three points are collinear the area encompassed by them is equal to 0.
The three given points are A(7, −2), B(5, 1) and C(3, 2k). It is also said that they are collinear and hence the area enclosed by them should be 0.
Δ=1/2|(7×1+5×2k+3×−2)−(5×−2+3×1+7×2k)| 0=1/2|(7+10k−6)−(−10+3+14k)| 0=1/2|−4k+8| 0=−4k+8 k=2
Hence the value of ‘k’ for which the given points are collinear is.
Δ=1/2|(x1y2+x2y3+x3y1)−(x2y1+x3y2+x1y3)|
If three points are collinear the area encompassed by them is equal to 0.
It is said that the point P(m,3) lies on the line segment joining the points and B(2,8). Hence we understand that these three points are collinear. So the area enclosed by them should be 0.
0=2m+8 m=−4
Hence the value of ‘m’ for which the given condition is satisfied is.
Δ=1/2|(x1y2+x2y3+x3y1)−(x2y1+x3y2+x1y3)|
If three points are collinear the area encompassed by them is equal to 0.
It is said that the point R(x, y) lies on the line segment joining the points P(a, b) and Q(b, a). Hence we understand that these three points are collinear. So the area enclosed by them should be 0.
0=ay+xa+b2−xb−by−a2 a2−b2=ax+ay−bx−by (a+b)(a−b)=(a−b)(x+y) (a+b)=(x+y)
Hence under the given conditions we have proved that.
Δ=1/2|(x1y2+x2y3+x3y1)−(x2y1+x3y2+x1y3)|
If three points are collinear the area encompassed by them is equal to 0.
The three given points are A(8,1), B(3,−4) and C(2,k). It is also said that they are collinear and hence the area enclosed by them should be 0.
Δ=1/2|(8×−4+3×k+2×1)−(3×1+2×−4+8×k)| 0=1/2|(−32+3k+2)−(3−8+8k)| 0=1/2|−25−5k|k=−5
Hence the value of ‘k’ for which the given points are collinear is.
Δ=1/2|(x1y2+x2y3+x3y1)−(x2y1+x3y2+x1y3)|
The three given points are A(a,2a), B(−2,6) and C(3,1). It is also said that the area enclosed by them is 10 square units. Substituting these values in the above mentioned formula we have,
Δ=1/2|(a×6+(−2)×1+3×2a)−((−2)×2a+3×6+a×1)|10=1/2|(6a−2+6a)−(−4a+18+a)|10=1/2|15a−20|20=|15a−20|4=|3a−4|
We have. Hence either
Or
Hence the values of ‘a’ which satisfies the given conditions are.
We know area of triangle formed by three points is given by
If three points are collinear the area encompassed by them is equal to 0.
The three given points are A(a,0), B(0,b) and C(1,1).
A =1/2|a(b−1)+1(0−b)|=1/2|ab−a−b|
It is given that
So we have,
Using this in the previously arrived equation for area we have,
Since the area enclosed by the three points is equal to 0, the three points need to be.
Coordinates of point B (1, 5) and C (7, −2)
TO FIND: The value of k
PROOF: point A divides the line segment joining P (−5, 1) and Q (3, −5) in the ratio k: 1
So the coordinates of A are
We know area of triangle formed by three points is given by Δ=12|(x1y2+x2y3+x3y1)−(x2y1+x3y2+x1y3)|
Now Area of ΔABC= 2 sq units.
Taking three points A , B (1, 5) and C (7, −2)
Hence
TO FIND: The third vertex.
PROOF: Let the third vertex be (x, y)
We know area of triangle formed by three points is given by Δ=12|(x1y2+x2y3+x3y1)−(x2y1+x3y2+x1y3)|
Now
Taking three points(x, y), (2, 1) and (3, −2)
Also it is given the third vertex lies on y = x+3
Substituting the value in equation (1) and (2) we get
Hence the coordinates of and
TO PROVE: that the points can never be collinear.
PROOF:
We know three points are collinear when
Now taking three points
Also it is given that
Hence area of triangle made by these points is never zero. Hence given points are never collinear.
TO FIND: the value of x
PROOF:
We know area of the triangles formed by three points is given by
Now
Area of triangle DBC taking D(x, 3x), B (−3, 5), C (4, −2)
Area of triangle ABC taking, A (6, 3), B (−3, 5), C (4, −2)
Also it is given that
Substituting the values from (1) and (2) we get
TO PROVE:
PROOF:
We know that three points are collinear if
Hence proved.
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