xiujianbo
春芽
共回答了16个问题采纳率:81.3% 举报
n是奇数,n=2k-1
则左边=sin(2kπ-π-π/6)
=sin(-π-π/6)
=sin(π-π/6)
=sin5π/6
=1/2
右边=cos(2nπ-π/3)=cos(-π/3)
=cosπ/3
=1/2
左边=右边
n是偶数,n=2k
则左边=sin(2kπ+π/6)
=sin(π/6)
=1/2
右边=cos(2nπ+π/3)
=cosπ/3
=1/2
左边=右边
综上
n是整数则sin[nπ+(-1)^n*π/6]=cos[2nπ+(-1)^n*π/3]
1年前
9