化简sin(4k-1/4)π-a+cos(4k+1/4)π-a

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化简sin(4k-1/4)π-a+cos(4k+1/4)π-a

化简sin(4k-1/4)π-a+cos(4k+1/4)π-a
化简sin(4k-1/4)π-a+cos(4k+1/4)π-a

化简sin(4k-1/4)π-a+cos(4k+1/4)π-a
k是奇数
k=2n-1
则原式=sin(kπ-π/4-a)+cos(kπ+π/4-a)
=sin(3π/4-a)+cos(5π/4-a)
=√2/2*cosa-√2/2*sina-√2/2cosa-√2/2*sina
=-√2sina
k是偶数
k=2n
则原式=sin(kπ-π/4-a)+cos(kπ+π/4-a)
=sin(-π/4-a)+cos(π/4-a)
=-√2/2*cosa-√2/2*sina+√2/2cosa+√2/2*sina
=0