角A+角B≤60°,证明sinA+sinB≤1

证明三角函数(和角公式)cosa(cosa-cosb)+sina(sina-sinb)=2sin²(a-b/2) 角A+角B≤60°,证明sinA+sinB≤1 证明sin(a+b)sin(a-b)=(sina+sinb)(sina-sinb) |sin(a+b)|小于等于|sina|+|sinb|的证明, 证明sina sin(a+2b) - sinb sin(b+2a) =sin(a+b)sin(a-b) 证明sin(2a+b)/sina-2cos(a+b)=sinb/sina 证明sin(2a+b)/sina-2cos(a+b)=sinb/sina 详细证明Sin(A+B)≤SinA+SinB是错误命题 证明三角函数等式sin(A+B)-sinA=2cos(A+B/2)sin(B/2) 如何证明sin(A-B)*sin(A+B)=sinA²-sinB² 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) 锐角三角形ABC中,三个内角A,B,C,两向量P=(2-2sinA,cosA+sinA) Q=（sinA-cosA,1+sinA）,P与Q是共线向量求数y=2sin^B+cos【（C-3B)/2】取最大值时,角B的大小,已算出角A=60°y=2sin^B+cos(C-3B)/2=2sin^B+cos(180°-A-4B)/2=2sin^B 已知cosB = cos θ*sinA,cosC = sinθ*sinA.θ为已知角.则sin^2 A + sin^2 B +sin^2C等于多少? sinA+sin(90°-A)+1/sinA-sin(90°-A)+1=cot(A/2) 请问这怎么证明, 如何证明sinA+sinB=2sin((A+B)/2)cos((A-B)/2) 证明:sin(2a+b)/sinb-2cos(a+b)=sinb/sina急 sinb/sina=cos(a+b),证明3sinb=sin(2a+b) sinA(cos(2A+B)+cosB)=cosA(sin(2A+B)-sinB)证明