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If the minute hand of a clock is 20 degrees behind the hour hand at this moment, then in 18 minutes, the minute hand will be how many degrees ahead of the hour hand?
 

 Feb 23, 2019
 #1
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The minute hand moves 2pi/60 =  pi/30 rads  every minute  = 6° every minute

 

The hour hand moves pi/6 rads every hour so it moves pi/360 rads every miniute = .5° every  minute

 

So...in 18 minutes....

 

The minute hand moves  18* 6 = 108°

 

And the hour hand moves   .5 * 18  =  9°

 

So....

 

The minute hand is    108 - ( 9 + 20)  =  108 - 29 = 79°  ahead of the hour hand after 18 mnutes

 

 

cool cool cool

 Feb 23, 2019
 #2
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Thank you so much CPhill

 Feb 23, 2019
 #3
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OK!!!

 

 

cool cool cool

CPhill  Feb 23, 2019

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