Shortly after 10 'o clock, the hands of a clock made a 90 degree angle. What's the time?
+36916 At 10:00 the hour hand is at 300 degrees ..... it moves 1/2 degree per minute
so the angle it forms with the 12 : oo position is
360 - 300 - 1/2 x
the minute hand moves 6 degrees per minute
the angle it forms with 12:00 is 6 x
summed they = 90 degrees
360-300-1/2 x + 6x = 90
60 + 5.5 x = 90
5.5x = 30
x = 5.45 minutes ( 5 min 27 sec) so at 10:05:27 the hands form a 90 degree angle
