证明2sin(π/4+x)sin(π/4-x)=cos2x

证明2sin(π/4+x)sin(π/4-x)=cos2x 证明∫( 0,π／2 ) (f sin x/(f sin x+f cos x) dx=π /4 证明一个sin&cos的等式证明 1+sin^2(x)+sin^4(x)+sin^6(x)=[1-sin^8(x)]/[cos^2(x)] 2sin(x+π/4)sin(x-π/4)=? sin^2(π/4 +x) sin(x+π/4) sinπ(x-1)=-sinπx如何证明 证明sin^4x-cos^4x=sin^2x-cos^2x 证明sin^2(x)+cos^2(x+30)+sin(x)cos(x+30)=3/4 怎样证明 sin X-cosX=√2（X-π/4) 求证:(sin 2x /(1-cos 2x) )·(sin x /(1+sin x))=tan (π/4-x/2). 证明：2sin(π/4+a)sin(π/4-a)=cos2a 证明2sin（π/4+α）sin（π/4-α）=cos2α 证明sinθ+cosθ=根号2sin(θ+π/4) cosγ+sinγ=根号2*sin(γ+π/4) 怎么证明 证明 2sin(π+x)cos(π-x)=sin2x f(x)=（1+cotx)sin^2x-2sin(x+π/4)sin(x-π/4)还有一题, sin(x+π/4)sin(x-π/4)等于什么?