sin(6/π-a)=1/3 sina=

sin(3π-a)=sina? 已知sin(π+a)=1/3,则sina= 1- sin(2π/3 - a)/sina 求证:(1)sin3a=3sina-4sin^3a 若sinA+cosA/sinA-cosA=2,则sin(A-5π)*sin(3π/2-A)等于? 已知tan{π/4+a}=3,求sina*sin(3π /2 +a)-sin^2a+1的值 f(x)=(2cos^2 a/2-sina-1)/(sin(a+π/3)sin(a-π/3) 证明sinA+sin(A+2π/3)+sin(A-2π/3)=0 已知sina=1/3,则sin(a+π/4)cos(a+π/4) sina+sin(120°-a)=根号3,怎样得到sin(a+30°)=1 sina(cosa)^3=1/4sin 2a+1/8sin 4a证明过程 已知a锐角 且sin(a-pi/6 )=1/3 求sina