Page 50 - Ganit Kaushal

Sol. (a) Acute angle (b) Obtuse angle (c) Right angle

(d) Reflex angle (e) Straight angle (f) Acute angles
Ex 3. Find the degree measures of ∠PQR, ∠PQS and ∠PQT in the following
figure. (NCERT)
Sol. Using the protractor, we get
∠PQR = 45°, ∠PQS = 100°, ∠PQT = 150°

Ex 4. Name the different angles in the adjoining figure and write their measures. (NCERT)

Sol. Observing the long marks and medium-sized marks covered by each angle, we conclude that:

∠POQ = 35°, ∠POR = 95°, ∠POS = 125°, ∠POT = 160°, ∠POU = 180°.
All other angles can be obtained with the help of these five angles as follows:
∠QOR = ∠POR – ∠POQ = 95° – 35° = 60°; ∠QOS = ∠POS – ∠POQ = 125° – 35° = 90°
∠QOT = ∠POT – ∠POQ = 160° – 35° = 125°; ∠QOU = ∠POU – ∠POQ = 180° – 35° = 145°
∠ROS = ∠POS – ∠POR = 125° – 95° = 30°; ∠ROT = ∠POT – ∠POR = 160° – 95° = 65°

∠ROU = ∠POU – ∠POR = 180° – 95° = 85°; ∠SOT = ∠POT – ∠POS = 160° – 125° = 35°
∠SOU = ∠POU – ∠POS = 180° – 125° = 55°; ∠TOU = ∠POU – ∠POT = 180° – 160° = 20°

Exercise 2.3

1. What kind of angle can be made by two adjacent fingers of your hand?
2. What is the angle between two consecutive spokes of a bicycle wheel if it has 36 spokes?
3. Identify the kind of angle in each of the following figures.

(a) (b) (c)

(d) (e) (f)

48 Mathematics-6