1 Answer

Linde · Answer 1 · 2023-06-19T19:48:01+0000

$\sin \left(-(7\pi)/(2) \right)=-\sin \left((7\pi)/(2) \right)$ (sine is an odd function)

$-\sin \left((7\pi)/(2) \right)=-\sin (3\pi)/(2)$ (sine has a period of
$2\pi$ )

$-\sin (3\pi)/(2)=-(-1)=1$ (unit circle)

$\cos \left(-(7\pi)/(2) \right)=\cos (7\pi)/(2)$ (cosine is an even function)

$\cos (7\pi)/(2)=\cos (3\pi)/(2)$ (cosine has a period of
$2\pi$ )

$\cos (3\pi)/(2)=0$ (use the unit circle)

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