Question

$25 \times {a}^{4} \div {5}^{ - 3 } \times 10 \times {a}^{ - 8}$
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Answer 1

Answer:

$\cos {}^{4} \frac{\pi}{8} + \cos {}^{4} \frac{3\pi}{8} + \cos {}^{4} \frac{5\pi}{8} + \cos {}^{4} \frac{7\pi}{8}$

Answer 2

Answer:

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