刘流星雨
幼苗
共回答了14个问题采纳率:78.6% 举报
1+cos100
=1+2cos²50-1
=2cos²50
cos50>0
所以根号下(1+cos100°)
=|√2cos50|
=√2*cos50
1-cos100
=1-(1-2sin²50)
=2sin²50
sin50>0
根号下(1-cos100°)
=|√2sin50|
=√2*sin50
所以原式=√2(cos50-sin50)
=-√2(sin50-cos50)
=-√2[√2sin(50-45)]
=-2sin5
1年前
8