sina+cosa=1/5 sin^2a+cos^2a=1 怎么求cosa 麻烦你了sina+cosa=1/5 sin^2a+cos^2a=1 怎么求cosa 麻烦你了

sina=2cosa,求(1)3sina+2cosa(2)sin²a+sina×cosa+3 sin(a+kπ)=2cos[a+(k+1)π].求5cosa+3sina/4sina-2cosa sin(a+kπ)=2cos[a+(k+1)π].求5cosa+3sina/4sina-2cosa 1:已知sina+cosa=根2求sina cosa sin(4方)a+cos(4方)的值2:已知:sina+cosa=1/5(0 已知(sina+cosa)/(sina-cosa)=3 则2sin'a+(sina-cosa)'=? sina+cosa/sina-cosa=2 求sin^2a-2sinacosa+1 已知sinA=1/5,求2sin(A+B)cosA-sin(2A+B) 已知(sina+cosa)/(sina-cosa)=2,则：(3sina+cosa)/(2sina+3cosa)=?sin^2a-2sinacosa+1=? 已知sina+cosa/sina-cosa=2,计算下列各式的值（1）3sina+cosa/2sina+3cosa(2)sin^a-2sinacosa+1. 已知sin=-3/5,那么(cosa+sina/cosa-sina)+(cosa-sina/cosa+sina)(a代表角, 已知sin a+cos a=1/2 sina*cosa=?cos a/sina+sina/cosa=? 若(sina+cosa)/(sina-cosa)=2,则sin(a-5派)*sin(3派/2-a)等于? 若(sina+cosa)/(sina-cosa)=2,则sin(a-5pai)*sin(3pai/2-a)等于? 若sinA+cosA/sinA-cosA=2,则sin(A-5π)*sin(7π/2-A)等于? 已知tan(π-a)=2,求值：（1）2sin+2cosa/7sina+cosa（2）sina*cosa（3）4cosa^2+3sina^2 sina+cosa=1/5 sin^2a+cos^2a=1 怎么求cosa 麻烦你了sina+cosa=1/5 sin^2a+cos^2a=1 怎么求cosa 麻烦你了 已知a为锐角sina-cosa=7/5 a∈（0,π）(1)tana(2)sina+cosa(3)sin^3a+cos^3a (1-tana)/(1+tana)=2求(1)sina+cosa/(sina+2cosa) (2)sina-cosa(3)sin^2a-3cos^2a+1