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been stuck on this question for months

 

 Jul 21, 2020
 #1
avatar+1041 
+1

This is very simple!!! Your 'stuckness' will disappear in a minute.laugh

 

∠AOB = ∠COB = 90º

 

1st      Find an angle  AOC          ∠AOC = ∠AOB + ∠COB

                                                     ∠AOC = 2[arccos( AO / OB )] = 108.6293306º

 

2nd     Find the central angle of a major arc ADC

 

                 That angle is    360º - ∠AOC = 251.3706694º

 

3rd       Find the length of ADC

 

                                         ADC = 2 * 7 * pi * ( 251.3706694 / 360 ) = 30.711

 Jul 21, 2020
 #2
avatar+25820 
+1

1/2 of the angle at O     arcos (7/12) = 54.31o

    so O is 108.6 o

        the arc you are looking for is   360 - 108.6 = 251.37o

 

Pi (2*7)  x   251.37/360 = .....

 Jul 21, 2020
edited by ElectricPavlov  Jul 21, 2020

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