证明sin^2a+sin^2β+1>sina*cosa+sina+sinβ

证明sin^2a+sin^2β+1>sina*cosa+sina+sinβ 【证明】Sin A+sin B=2Sin 22 懂得进.证明,sina+sin(a+b)+sin(a+2b)+...sin(a+nb)=sin(a+ab/2)sin[(n+1)b/2]/sin(b/2) 证明 sin^2A+sin^2B-sin^2A*sin^2B+cos^2A*cos^2证明 sin^2A+sin^2B-sin^2A*sin^2B+cos^2A*cos^2B=1 sin^2a+sin^2β-sin^2a*sin^2β+cos^2a*cos^2β=1 证明恒等式?各位高手 教教我 证明sin(a+b)sin(a-b)=sin^2 a-sin^2 b, 证明Cos^A-Sin^A=1-2Sin^A=2Cos^A-1=cos^a-sin^a 证明cosα(cosα-cosβ)+sinα(sinα-sinβ)=2sin^2(α-β/2)第二个 证明sin(α+β)cosα-1/2[sin(2α+β)-sinβ]=sinβ 证明：sin(2α+β)/sinα - 2cos(α+β)=sinβ/sinα 证明:sin^4a+cos^4a=1-1/2sin^22a 证明tan a/2=sin a/(1+cos a) 证明：1+cos^2a/sin^2a=1/sin^2aRT sina(cosa)^3=1/4sin 2a+1/8sin 4a证明过程 三角函数!证明1/2(cos2B-cos2A)=sin(A+B)×sin(A-B) 证明sina sin(a+2b) - sinb sin(b+2a) =sin(a+b)sin(a-b) 三角形ABC中证明 COSA+COSB+COSC=1+4SIN(A/2)*SIN(B/2)*SIN(C/2) 三角形ABC中证明 COSA+COSB+COSC=1+4SIN(A/2)*SIN(B/2)*SIN(C/2) 求高中一道不等式和三角函数题的解1知函数y=x平方-4ax+2a+30的值总大于0,求a的取值范围2证明：sin(α+β)som(α-β) = sin平方α - sin平方β2证明：sin(α+β)sin(α-β) = sin平方α - sin平方β