sin a+sin 2a /1+cos a+cos 2a 化简.

化简Sin A + Sin 2A / 1+cos A + 证明Cos^A-Sin^A=1-2Sin^A=2Cos^A-1=cos^a-sin^a 化简：sin 2a/(1+cos 2a) * cos a/(1+cos a) 化简:sin(-a)cos(2π+a)sin(-a-π) 化简 1-sin^4a-cos^4a/cos^2a-cos^4a 化简(1-sin^6 a-cos^6 a)/(cos^2 a-cos^4 a)== 化简sin^2a-cos^2a 化简sin a+cos a sin^2a+sin^2a.cos^2a+cos^2a化简 化简cos^2(a+15)+sin^2(a-15))+sin(a+180)cos(a-180) 化简[cos(a-π)/sin(π-a)]sin(a-π/2)cos(π/2+a)= 化简~cos^2(a+15)+sin^2(a-15)+sin(a+180)cos(a-180)