sin(π/2-x) 和cos（π/2-x）怎么算

2个回答

利用三角诱导公式公式,口诀为奇变偶不变,符号看象限.首先看π/2的系数是奇数的话改变函数名,正弦变为余弦,余弦变为正弦；再把x看做锐角,π/2-x也是锐角,所以sin(π/2-x)=cosx；
cos（π/2-x）=sinx

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