[求助] 三角函數 sin(90+x)= cosx
想請問各位老師高手
我看書上有一個公式
sin(90+x) = cosx
請問這個x有何限制嗎?
我遇到一題我的想法是 sin(2070) = sin( 90*23 + 0 ) = cos0 = 1
但另一個做法 sin(2070) = sin(360*5 + 270) = sin(270)= -1
我是哪出問題?
謝謝
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