From 10: 30 in the morning to 1 1: 30, the hour hand passed a word, that is, 360/ 12 = 30, and the minute hand passed 180. There are two moments when the hour hand and the minute hand are at right angles, one of which is at 10: 30.
10: 30: the scale of the hour hand is between 10 and1,and the angle with the minute hand is 360÷ 12? X( 10.5—6)= 135
Suppose: walk for a minute, the first time is a right angle; After walking for b minutes, make a right angle for the second time and get the following formula.
135? +? Answer? /? 12? x? (360? /? 60)—a? x? (360? /? 60)=90
b? x? (360? /? 60)— 135? —? b/? 12? x? (360? /? 60)=90
Get: a=90/ 1 1=8? ; b=450/ 1 1=40?
10:30+8? = 10:38? So the first right angle is 10: 38? 2/ 1 1? minute
10:30+40? = 1 1: 10? So the second right angle is at 1 1 point1011min.