求证 tan(2π-X)sin(-2π-X)cos(6π-X)/ sin(X+3π/2)*cos(X+3π/2)=-tanX
问题描述:
求证 tan(2π-X)sin(-2π-X)cos(6π-X)/ sin(X+3π/2)*cos(X+3π/2)=-tanX
答
tan(2π-x) sin(-2π-x) cos(6π-x) / sin(x+3π/2)*cos(x+3π/2)
=(-tanx) (-sinx) cosx / (-cosx) sinx
=-tanx