若tana=-2,则1/4sin^2a+2/5cos2a=

k=(2sin^2a+sin2a)/(1+tana) 则sin(a-3.14/4)的值 证明cos^4 a-sin^4 a=cos^2(1-tana)(1+tana) 证明sin^4 a+cos^4 a=cos^2(1-tana)(1+tana) 若tana=2,则1/4sin^2a+1/2sin2a= 若tana=-2,则1/4sin^2a+2/5cos2a= 若tanA=2,则1/4Sin^A+1/2Sin2A= 若tana=2则sin^2a+sinacosa 若tana=2,则sin²a= 已知tana/(tana-1)=-1,则sin^2a+sinacosa+2= tanA=2 求(sin^2 A+ sinAcosA)/(tanA+1+sin^2 A) 急 . 求证sin^2a*tana+cos^2a*1/tana+2sina*cosa=tana+1/tana 若tana=1/3,则sin^3 a+2cos^ 3 a/sin^3 a-2cos^3 a sin(a+b)=1/2,sin(a-b)=1/3,则tana/tanb=? sin(a+b)=1/2,sin(a-b)=1/3,则tana/tanb=? 已知sin(a+x)=1/2,sin(a-x)=1/3,则tana/tanx 已知tana=2,则2/3(sin*2)a+1/4(cos*2)a=? 若tana=√3 ,则cos2a-cos^2 a / sin^2 a-1= 已知tana=3,则sin^2a-4sinacosa+4cos^2a+1=