已知sin(π/3-X),则cos(5π/6-X)=?
问题描述:
已知sin(π/3-X),则cos(5π/6-X)=?
答
cos(5π/6-X)
=-cos[π-(5π/6-X)]
=-cos(x+π/6)
=-sin[π/2-(x+π/6)]
=-sin(π/3-X)