Correct answers are a) and d)
\(\alpha=- \frac{\pi}{4}\)
Coterminal angles: \(\alpha+k\pi,\,k\in Z\)
\(- \frac{\pi}{4}+2\pi=- \frac{\pi}{4}+ \frac{8\pi}{4} = \frac{7\pi}{4}
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\\- \frac{\pi}{4}-2\pi=- \frac{\pi}{4}- \frac{8\pi}{4} = -\frac{9\pi}{4}\)