liwenjixie96
春芽
共回答了16个问题采纳率:68.8% 举报
当k为偶数时sin(kπ+a)=sina,sin(a-kπ)=sina,
cos(a-Kπ)=cosa
sin(kπ+a)+sin(a-kπ)除以sin(a+Kπ)cos(a-Kπ)
=2sina/sinacosa=2/cosa;
当k为奇数时sin(kπ+a)=-sina,sin(a-kπ)=-sina,
cos(a-Kπ)=-cosa
sin(kπ+a)+sin(a-kπ)除以sin(a+Kπ)cos(a-Kπ)
=-2sina/sinacosa=-2/cosa;
1年前
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