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Shaded = 18 Square Units

Find the Blue Area ( Animation )

Total = 450 Square Units

sin AEF = 0.292828901981

Radius R = 21.25 = 85 / 4

Ratio of AC / DE = 3

Radius R = 3.5

Another Approach

Blue Area = 6 + ( 12 / X )

Orange = 64.2743338823

Solution = 1.61803398875