计算:sinA²1°+sin²3°+sin²5°+...+sin²87°+sin

计算：sin²1°+sin²2°+sin²3°...+sin²45°+sin&# 数列求和 sin²1°+sin²2°+sin²3°+.+sin²88°+sin& 证明sin(a+b)sin(a-b)=sin²a-sin² b,并用该式计算sin²20° sin²1°+sin²2°+sin²89°+sin²88°= sin²1°+sin²2°+……sin²88°+sin²89° 尽快 我今天将就要!化简（计算）1、Sin²10°+Sin²20°+Sin²30°+Sin 计算,tan91°tan92°……tan179°/sin²1°+sin²2°+……+sin² sina+sin(120°-a)=根号3,怎样得到sin(a+30°)=1 Sin（30°-a）＝1/3,求Sina sin²70°怎么化简 sin²60° 怎么算 求sin²20°+sin80°sin40°,并且要用sin(α+β)sin(α-β)=sin²α-s