Prove that, ^4 8 + ^4 3 8 + ^4 5 8 + ^4 7 8 = 3 2

MATHEMATICS · Subjective · CBSE · Mathematics · Trigonometric Functions · Trigonometric Functions

Problem

Prove that, cos⁡4π8+cos⁡43π8+cos⁡45π8+cos⁡47π8=32\cos^4 \frac{\pi}{8} + \cos^4 \frac{3\pi}{8} + \cos^4 \frac{5\pi}{8} + \cos^4 \frac{7\pi}{8} = \frac{3}{2}

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