Question 204012
Radius  =  dia /2 = 4.5/2=2.25
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central angle  is  360 /8 =45.
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drawing  a  rough  sketch,  the  median  to  the  line  between  the  holes,from  the  center  if  the  circle,  is  a  perpendicular  bisector  of  that  line.
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Let  d  =  distance  of  the line  between  holes,,then
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sin(45/2) = (d/2) / 2.25
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(sin  22.5)(2.25) = d/2
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d=1.722
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check sin  a= 1.722/2/2.25 =.3827,,,a=22.5,,,,ok