# RS Aggarwal Class 6 Math Thirteenth Chapter Angels And Their Measurement Exercise 13B Solution

## EXERCISE 13B

Magnitude Angle: The magnitude of an angle is amount of rotation through which one of the arms must be rotated about the vertex to bring it to the position of the other.

Right Angle: A quarter turn of a ray OA about O describes an angle called a right angle. 1 right angle = 90o

#### VARIOUS TYPES OF ANGLES Acute Angle: An angle whose measure is more than 0o but less than 90o is called acute angle.

Right Angle: An angle whose measure is 90o is called right angle.

Obtuse Angle: An angle whose measure is more than 90o but less than 180o is called an obtuse angle.

Straight Angle: An angle whose measure is 180o is called a straight angle.

Reflex Angle: An angle whose measure is more than 180o but less than 360o is called a reflex angle.

Complete Angle: An angle whose measure is 360o is called a complete angle.

Zero Angle: The angle whose measure is 0o is called a zero angle.

(1) State the type of each of the following angles: Ans: (i) Obtuse angle

(ii) Right angle

(iii) Straight angle

(iv) Reflex angle

(v) acute angle

(vi) Complete angle

(2) Classify the angles whose magnitudes are given below:

(i) 30 Ans: Acute

(ii) 91o

Ans: Obtuse

(iii) 179o

Ans: Obtuse

(iv) 90o

Ans: Right

(v) 181o

Ans: Reflex

(vi) 360o

Ans: Complete

(vii) 128o

Ans: Obtuse

(viii) (90.5)o

Ans: Obtuse

(ix) (38.3)o

Ans: Acute

(x) 80o

Ans: Acute

(xi) 0o

Ans: Zero

(xii) 15o

Ans: Acute

(3) How many degrees are there in

(i) One right angle?

Ans: 90o

(ii) Two right angles?

Ans: 180o

(iii) Three right angles?

Ans: 270o

(iv) Four right angles?

Ans: 360o (4) How many degrees are there in the angle between the hour hand and the minute hand of a clock, when it is

(i) 3 o’clock

Ans: 90o (ii) 6 o’clock

Ans: 180o (iii) 12 o’clock

Ans: 0o (iv) 9 o’clock

Ans: 90o (5) Using only a ruler, drawn an acute angle, an obtuse angle and a straight angle? (i) ∠AOB is an acute angle.
(ii) ∠POQ is an obtuse angle.
(iii) ∠XOY = 180 degree = a straight angle.   Updated: May 30, 2022 — 12:36 pm