NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRev

Mathematics (Maths) Class 6

Created by: Praveen Kumar

Class 6 : NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRev

The document NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRev is a part of the Class 6 Course Mathematics (Maths) Class 6.
All you need of Class 6 at this link: Class 6

Exercise 5.4 
Ques 1: What is the measure of 
(i) a right angle? 
(ii) a straight angle? 
Ans: (i) 90o

NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRev
(ii) 180o

NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRev

Ques 2: Say True or False: 
(a) The measure of an acute angle < 90. 
(b) The measure of an obtuse angle < 90. 
(c) The measure of a reflex angle > 180. 
(d) The measure of on complete revolution = 360. 
(e) If m∠A = 53o and m∠B = 35o then m∠A > m∠B. 
Ans: (a) True
(b) False
(c) True
(d) True
(e) True

Ques 3: Write down the measure of: 
(a) some acute angles 
(b) some obtuse angles 
(give at least two examples of each)
Ans: (a) 35o, 20o 
(b) 110o, 135o

Ques 4: Measure the angles give below, using the protractor and write down the measure: 

NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRev

NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRev

NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRev

NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRev
Ans: (a) 40o
(b) 130o
(c) 90o
(d) 60o

Ques 5: Which angle has a large measure? First estimate and then measure: 

NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRev
Measure of angle A = ?
Measure of angle B = ?
Ans: ∠B has larger measure. ∠A = 40o and ∠B = 65o

Ques 6: From these two angles which has larger measure? Estimate and then confirm by measuring them: 
Ans: Second angle has larger measure.

NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRev

Ques 7: Fill in the blanks with acute, obtuse, right or straight: 
(a) An angle whose measure is less than that of a right angle is ________________. 
(b) An angle whose measure is greater than that of a right angle is ________________. 
(c) An angle whose measure is the sum of the measures of two right angles is ________________. 
(d) When the sum of the measures of two angles is that of a right angle, then each one of them is ________________. 
(e) When the sum of the measures of two angles is that of a straight angle and if one of them is acute then the other should be ________________. 
Ans: (a) acute angle
(b) obtuse angle
(c) straight angle
(d) acute angle
(e) obtuse angle

Ques 8: Find the measure of the angle shown in each figure. (First estimate with your eyes and then find the actual measure with a protractor). 

NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRevNCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRevNCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRevNCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRev
Ans: (i) 30o
(ii) 120o
(iii) 60o
(iv) 150o

Ques 9: Find the angle measure between the hands of the clock in each figure: 

NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRevNCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRevNCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRev 
Ans: (i) 90 (Right angle)
(ii) 30 (Acute angle)
(iii) 180 (Straight angle)

Ques 10: Investigate: 
In the given figure, the angle measure 30. Look at the same figure through a magnifying glass. Does the angle becomes larger? Does the size of the angle change? 

NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRev
Ans: No, the measure of angle will be same.

Ques 11: Measure and classify each angle: 

NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRev

Angle

Measure

Type

∠AOB

 

 

∠AOC

 

 

∠BOC

 

 

∠DOC

 

 

∠DOA

 

 

∠DOB

 

 

Ans:

Angle

∠AOB

∠AOC

∠BOC

∠DOC

∠DOA

∠DOB

Measure

40°

130°

90°

90°

140°

180°

Type

Acute

Obtuse

Right

Right

Obtuse

Straight


Exercise 5.5 
Ques 1: Which of the following are models for perpendicular lines: 
(a) The adjacent edges of a table top. 
(b) The lines of a railway track. 
(c) The line segments forming the letter ‘L’. 
(d) The letter V. 
Ans: (a) Perpendicular
(b) Not perpendicular
(c) Perpendicular
(d) Not perpendicular

Ques 2: Let NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRev  be the perpendicular to the line segment NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRev. Let NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRev and NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRevintersect in the point A. What is the measure of ∠PAY? 
Ans: 

NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRev

Ques 3: There are two “set-squares” in your box. What are the measures of the angles that are formed at their corners? Do they have any angle measure that is common? 
Ans: One set-square has 45 ,90 ,45 and other set-square has 60 ,90 ,30 . They have 90 as common angle.

Ques 4: Study the diagram. The line l is perpendicular to line m. 

NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRev
(a) Is CE = EG? 
(b) Does PE bisect CG? 
(c) Identify any two line segments for which PE is the perpendicular bisector. 
(d) Are these true? 
(i) AC > FG 
(ii) CD = GH 
(iii) BC < EH 
Ans: (a) Yes, both measure 2 units.
(b) Yes, because CE = EG
NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRev
(d) (i) True, (ii) True, (iii) True

Exercise 5.6 
Ques 1: Name the types of following triangles: 
(a) Triangle with lengths of sides 7 cm, 8 cm and 9 cm. 
(b) ΔABC with AB = 8.7 cm, AC = 7 cm and BC = 6 cm. 
(c) ΔPQR such that PQ = QR = PR = 5 cm. 
(d) ΔDEF with m∠D = 90o 
(e) ΔXYZ with m∠Y = 90o and XY = YZ 
(f) ΔLMN with m∠L = 30o , m∠M = 70o and m∠N = 80o
Ans: (a) Scalene triangle
(b) Scalene triangle
(c) Equilateral triangle
(d) Right-angled triangle
(e) Isosceles right-angled triangle
(f) Acute-angled triangle

Ques 2: Match the following: 

Measure of Triangle
Types of Triangle
(i) 3 sides of equal length
(a) Scalene
(ii) 2 sides of equal length
(b) Isosceles right angle
(iii) All sides are of different length
(c) Obtuse angle
(iv) 3 acute angles
(d) Right angle
(v) 1 right angle
(e) Equilateral
(vi) 1 obtuse angle
(f) Acute angle
(vii) 1 right angle with two sides of equal length
(g) Isosceles

Ans: (i) → (e)
(ii) → (g)
(iii) → (a)
(iv) → (f)
(v) → (d)
(vi) → (c)
(vii) → (b)

Ques 3: Name each of the following triangles in two different ways: (You may judge the nature of angle by observation) 

NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRev
NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRev
NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRev
NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRev
NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRev
NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRev
Ans: (a) Acute angled triangle and Isosceles triangle
(b) Right-angled triangle and scalene triangle
(c) Obtuse-angled triangle and Isosceles triangle
(d) Right-angled triangle and Isosceles triangle
(e) Equilateral triangle and acute angled triangle
(f) Obtuse-angled triangle and scalene triangle

Ques 4: Try to construct triangles using match sticks. Some are shown here. 

NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRev
Can you make a triangle with: 
(a) 3 matchsticks? 
(b) 4 matchsticks? 
(c) 5 matchsticks? 
(d) 6 matchsticks? (Remember you have to use all the available matchsticks in each case) 
If you cannot make a triangle, think of reasons for it. 
Ans: (a) 3 matchsticks This is an acute angle triangle and it is possible with 3 matchsticks to make a triangle because sum of two sides is greater than third side.
(b) 4 matchsticks This is a square, hence with four matchsticks we cannot make triangle.

NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRev

(c) 5 matchsticks This is an acute angle triangle and it is possible to make triangle with five matchsticks, in this case sum of two sides is greater than third side.

NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRev

(d) 6 matchsticks This is an acute angle triangle and it is possible to make a triangle with the help of 6 matchsticks because sum of two sides is greater than third side.

NCERT Solutions(Part - 2) - Understanding Elementary Shapes Class 6 Notes | EduRev

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