证明：(sinx)^2+sin(x+60度）^2+sin(x+120度）^2=3/2最好快点呵

证明:sin2x=2sinx*cosx为什么sin(x+x)=sinx*cosx+cosx*sinx? 证明x∈(0,π/2),cos(cosx)>sin(sinx) 证明(4sinx+3)/(sin^2x+1) 证明成立：[cos(3x)-sin(3x)]/(cosx+sinx)=1-2sin(2x). 证明 [sin(2x+y)/sinx]-2cos(x+y)=siny/sinx 证明sin(x+y)sin(x-y)=（sinx）^2-(siny）^2. 利用cosx=sin(π/2-x),sin'x=cosx,证明(cosx)'=-sinx 证明sin(x+y)sin(x-y)=sinx-siny 1-2sinx*sin(60+x)sin(60-x) 证明cosx(cosx-cosy)+sinx(sinx-siny)=2sin(x-y)/2 y=[√（1+sin^2x)+sinx+1]/[√（1+sin^2x)+sinx-1]判断并证明奇偶性 化简sin(x+60)+2sinx-60 2sinx=sin(60-x),求sinx的值 证明(sinx/x)^2 (sinX+sinθ) .(Sinx-sinθ)=sin(x+θ).cos(x-θ)证明 怎么证明(1/2)sinx=sin(x/2)cos(x/2)怎么证明(1/2)sinx=sin(x/2)cos(x/2) 如何证明sin(sin(sinx)) 证明：(sinx)^2+sin(x+60度）^2+sin(x+120度）^2=3/2最好快点呵