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Prove that the triangle is right angled - [ILL 1971]

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January 1, 2011
trigonometry

Problem Statement

Let A,B,A, B, and CC denote the angles of a triangle. If sin2A+sin2B+sin2C=2\sin^2 A + \sin^2 B + \sin^2 C = 2, prove that the triangle is right-angled.