sin²120°+cos180°+tan45°-cos²330°+sin(-210°)

题目

sin²120°+cos180°+tan45°-cos²330°+sin(-210°)
急用,注意 是cos²330°

答案

sin120°=sin60°=√3/2
cos180° = -1
tan45°=1
cos330° = cos30° = √3/2
sin(-210°) = sin(-360°+150°)=sin150°=sin30°=1/2
原式=3/4 -1 + 1 - 3/4 + 1/2 = 1/2