



 
Hi Bill, The circumference of a circle is 2 π r where r is the radius. The length of the circular arc is only a fraction of the circumference because the central angle of 40 degrees is only a fraction of a complete revolution, 360 degrees. Since 360/40 = 9 it takes 9 of these sectors to fill the circle and thus the circumference must be 9 times the chord length. Hence
What is r? Penny  


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