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Find the angle between the hour hand and minute hand of a clock when it is 9:20.

 Jun 16, 2020
 #1
avatar+302 
+2

At 9:40, the minute hand is at 4 and the hour hand is between 9 and 10. 

There is \(30 ^\circ*5=150^\circ\)between the minute hand and 9 o'clock. 

The hour hand is \(\frac{20}{60}*30^\circ=10^\circ\) past 9 o'clock.

So our answer is \(150^\circ+10^\circ=160^\circ\)

 Jun 16, 2020
 #2
avatar+26007 
+1

Hour hand moves .5 degree per minute and starts at 270 degrees at nine o'clock

    So hour hand is at.   270 + (20*.5)= 280o

       Minute hand is at 120 degrees  at 20 after

280-120=160 between the hands....

 Jun 16, 2020
 #3
avatar+25532 
+1

Find the angle between the hour hand and minute hand of a clock when it is 9:20.

 

\(\begin{array}{rcll} \Delta\alpha^{\circ} &=& 330 \times t^h \pmod{360^{\circ}} \quad | \quad \mathbf{t^h=9+\dfrac{20}{60} = \dfrac{28}{3}\ h } \\ &=& 330 \times \dfrac{28}{3} \pmod{360^{\circ}} \\ &=& 3080^{\circ} \pmod{360^{\circ}} \\ &=& \mathbf{200^{\circ}} \qquad (\text{greater angle)} \\ &=& \mathbf{360^\circ-200^{\circ}=160^\circ} \qquad (\text{smaller angle)} \\ \end{array} \)

 

laugh

 Jun 17, 2020

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