Question

訪客0

我想請問siny和cosy的y為什麼分別屬於(-90~90),(0~180)

[Inverses of Trigonometric Functions sin x and cos x]
(1) y = sin-' x x A x = sin y for | x | < 1 and y E[-a/2, a/2]
(2) y = cos-' x x = cos y for |x| = 1 and y € [0, 1]
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