If A + B + C = 2π, prove that cos 2 B + cos 2 C - sin 2 A - 2 cos A cos B cos C = 0 This question has not been answered yet! Don't worry! You can check out similar questions with solutions below Prove that cos^32x+3cos2x=4(cos^6-sin^6)Prove that cos 105° + cos 15° = sin 75° − sin 15°.prove that . cos^4A - cos^2A = sin^4A - sin^2AProve: (1 – cosθ + sinθ) (1 + cosθ + sinθ) = 2 sin θ (1 + ... Prove that cos a / 1+ sin a + 1+sin a/ cos a= 2 sec a