sin²48°+sin²42°-tan48°tan42°=

锐角三角形函数计算计算：sin的平方27°+tan48°×tan42°-cot21°×cos90°+sin的平方63° 懂的来.1.求值:tan72° tan42° (根号3/3)tan72°tan42°= sin²1°+sin²2°+sin²89°+sin²88°= 计算：sin²1°+sin²2°+sin²3°...+sin²45°+sin&# 数列求和 sin²1°+sin²2°+sin²3°+.+sin²88°+sin& 化简（1）tan18°+tan42°+√3tan18°tan42° 证明sin(a+b)sin(a-b)=sin²a-sin² b,并用该式计算sin²20° sin²1°+sin²2°+……sin²88°+sin²89° 求sin²20°+sin80°sin40°,并且要用sin(α+β)sin(α-β)=sin²α-s sin²20°+sin²80°-sin20°sin80°=? sin²40°+sin²50°+2-tan135°怎么算= sin²48°+sin²42°-tan²44°×tan²45°×tan²