Find the number of right angles turned through by the hour hand of a clockwhen it goes from: (a) 3 to6 (b) 2 to8 (c) 5 to11 (d) 10 to1 (e) 12 to9 (f) 12 to 6

The hour hand of clock revolves by 360 degree or 4 right angles in 1 complete round.

(a) The hour hand of a clock revolves by 90 degree of 1 right angle when it goes from 3 to 6. Hence one right angle

(b) The hour hand of a clock revolves by 180 degree of 2 right angles when it goes from 2 to 8. Hence  two right-angles

(c) The hour hand of a clock revolves by 180 degree of 2 right angles when it goes from 5 to 11.  Hence two right angles

(d) The hour hand of a clock revolves by 90 degree of 1 right angle when it goes from 10 to 1. Hence one right angle

(e) The hour hand of a clock revolves by 270 degree of 3 right angles when it goes from 12 to 6. Hence three right angles.