Question

the time between 7: to 7:30 such that the hour hand and the minute hand of a clock are perpendicular to each other is

Answer 1

Perpendicular means an angle of 90° between the hour hand at 7 and the minute hand ( which is in between 7:00 to 7:30)

if we take 15mins rotation the hand covers a total of 90°

∴For 5mins it covers 30°

⇒That for an angle of 90° between the hour hand at 7 O'clock and the minute hand which should be between 7 and 7.30.

the minute hand should be placed 15mins before the 7 O'clock time

i.e the minute hand should be placed on 4 i.e (20mins symbol)

At 7:20 the minute hand would be perpendicular to the hour hand.