一道数学题 已知cos(π/4-α)=根号下3/3 求sin(π/α) ,sin(3π/4-α)
问题描述：
一道数学题 已知cos(π/4-α)=根号下3/3 求sin(π/α) ,sin(3π/4-α)
答
∵cos(π/4-α)=√3／3∴sin²(π/4-α)=1-cos²(π/4-α)=2／3∴sin(π/4-α)=±√6／3又∵sin(3π/4-α)=sin[π-(π/4+α)]=sinπcos(π/4-α)-cosπsin(π/4-α）∴ sin(3π/4-α) = ±√6／3 sin(π/α)...