# Exercise 5.4 - Chapter 5 Understanding elementary shapes class 6 ncert solutions Maths - SaraNextGen [2024]

Question 1:

What is the measure of (i) a right angle? (ii) a straight angle?

(i) The measure of a right angle is 90°.

(ii) The measure of a straight angle is 180°.

Question 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 one complete revolution = 360°

(e) If m∠A = 53° and m∠B = 35°, then m∠A > m∠B.

(a) True

The measure of an acute angle is less than 90°.

(b) False

The measure of an obtuse angle is greater than 90º but less than 180º.

(c) True

The measure of a reflex angle is greater than 180°.

(d) True

The measure of one complete revolution is 360º.

(e) True

Question 3:

Write down the measures of

(a) Some acute angles. (b) Some obtuse angles.

(Give at least two examples of each).

(a) 45°, 70°

(b) 105°, 132°

Question 4:

Measure the angles given below using the Protractor and write down the measure.

(a) 45º

(b) 120º

(c) 90º

(d) 60º, 90º, and 130º

Question 5:

Which angle has a large measure? First estimate and then measure.

Measure of angle A =

Measure of angle B =

Measure of angle A = 40º

Measure of angle B = 68º

∠B has the greater measure than ∠A.

Question 6:

From these two angles which has larger measure? Estimate and then confirm by measuring them.

The measures of these angles are 45º and 55º. Therefore, the angle shown in 2nd figure is greater.

Question 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 _______.

(a) Acute angle

(b) Obtuse angle (if the angle is less than 180º)

(c) Straight angle

(d) Acute angle

(e) Obtuse angle

Question 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).

The measures of the angles shown in the above figure are 40º, 130º, 65º, 135º respectively.

Question 9:

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

(a) 90°

(b) 30°

(c) 180°

Question 10:

Investigate

In the given figure, the angle measures 30°. Look at the same figure through a magnifying glass. Does the angle become larger? Does the size of the angle change?

The measure of this angle will not change.

Question 11:

Measure and classify each angle:

 Angle Measure Type ∠AOB – – ∠AOC – – ∠BOC – – ∠DOC – – ∠DOA – – ∠DOB – –