(-tana)*sin(-a)*cosa怎么得的sin2a

(-tana)*sin(-a)*cosa怎么得的sin2a 已知sin(60-a)=4 求cosa?tana?-5 求证sin^2a*tana+cos^2a*1/tana+2sina*cosa=tana+1/tana 求证1+2sina cosa/sin^2a-cos^2a=tana+1/tana-1 求证：1+2sina cosa /sin^2a -cos^2a = tana +1/tana -1. 化简：sin^2a*tana+cos^2a/tana+2sina*cosa 求证 sin²a*tana+cos²a*cota+2sina*cosa=tana+cota tanA=1/ tanA=sinA/ cotA=cosA/ sin^2A+cos^2A= 求证cos^3a(1+tana)+sin^3a(1+1/tana)=sina+cosa 已知tana=-3,求sina+2cosa/cosa-3sina和sin^2a-sinacosa 证明(sin2A+sin^2A)/（2cos2A+2sin^2A+cosA ）=tanA 已知tana=2,则(sin^3a+cosa)/(sin^3a+sina)的值为? tana=3,则(2sin^3a+cosa)/(cos^3a-sin^2a×cosa)= tana=2,则(sin^3a+cosa)/(sin^3+sina)的值 sin^2a*tana+cos^2a*cota+2sina*cosa求大神帮助sin^2a*tana+cos^2a*cota+2sina*cosa 要化简 (1-tana)/(1+tana)=2求(1)sina+cosa/(sina+2cosa) (2)sina-cosa(3)sin^2a-3cos^2a+1 已知tana/tana-1=-1,求下列各式的值（1）sina-3cosa/sina+cosa(2)sin^2a+sina*cosa+2 已知tana/（tana-1）=-1,求下列各式的值（1）sina-3cosa/sina+cosa(2)sin^2a+sina*cosa+2