Q.5 Find the number of right angles turned through by the hour hand of a clock when it goes from
(a)3 to 6
(b) 2 to 8
(c) 5 to 11
(d) 10 to 1
(e) 12 to 9
(f) 12 to 6

(a) 3 to 6 = 6 - 3 = 3 hour
In one revolution = 12 hour
No. of revolution = 3 / 12 = 1/4 revolution.
In one revolution = 4 right angle
\(\therefore \) 1/4 revolution = (1\4) × 4 = 1 right angle
(b) 2 to 8 = 8 - 2 = 6 hour
In one revolution = 12 hour
No. of revolution = 6 / 12 = 1/2 revolution.
In one revolution = 4 right angle
\(\therefore \) 1/2 revolution = (1\2) × 4 = 2 right angle
(c) 5 to 11 = 11 - 5 = 6 hour
In one revolution = 12 hour
No. of revolution = 6 / 12 = 1/2 revolution.
In one revolution = 4 right angle
\(\therefore \) 1/2 revolution = (1\2) × 4 = 2 right angle
(d) 10 to 1 I.e., 10 to 13 = 13 - 10 = 3 hour
In one revolution = 12 hour
No. of revolution = 3 / 12 = 1/4 revolution.
In one revolution = 4 right angle
\(\therefore \) 1/4 revolution = (1\4) × 4 = 1 right angle
(e) 12 to 9 I.e., 0 to 9 = 9 - 0 = 9 hour
In one revolution = 12 hour
No. of revolution = 9 / 12 = 3/4 revolution.
In one revolution = 4 right angle
\(\therefore \) 3/4 revolution = (3\4) × 4 = 3 right angle
(f) 12 to 6 = 6 - 0 = 6 hour
In one revolution = 12 hour
No. of revolution = 6 / 12 = 1/2 revolution.
In one revolution = 4 right angle
\(\therefore \) 1/2 revolution = (1\2) × 4 = 2 right angle