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P ( BCD ) / P ( ABC ) = 7 / 9

tan α = 1 / 2 = 0.5

Blue Area = 14.7614538495

tan α = 2.2360679775

B / A = 2.2360679775

Purple / Gold = 2 : 1 = 2

X = BEC = 30°

Blue Area = 27 cm ²

Red Vertex is on Semicircle

X = GH = 60