tan(x/2)=t,求证sinx=2t/(1+t²)
证明:sinx=2sin(x/2)cos(x/2)=2sin(x/2)cos(x/2)/[sin²(x/2)+cos²(x/2)]
=2tan(x/2)/[1+tan²(x/2)]=2t/(1+t²)
tan(x/2)=t,求证sinx=2t/(1+t²)
证明:sinx=2sin(x/2)cos(x/2)=2sin(x/2)cos(x/2)/[sin²(x/2)+cos²(x/2)]
=2tan(x/2)/[1+tan²(x/2)]=2t/(1+t²)