Forcing a Right Angle

★ 7/10trigonometry Trigonometric Identities Triangle Geometry

Problem

The angles of a non-obtuse triangle $ABC$ satisfy

\cos^2 A + \cos^2 B = \sin C.

Prove that $C$ is a right angle.

Answer

Solution

Difficulty	7/10
Topics	trigonometry, Trigonometric Identities, Triangle Geometry

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