三角函数诱导公式已知sin(π+α)=-1/3,计算1.cos(5π+α)

问题描述:

三角函数诱导公式已知sin(π+α)=-1/3,计算1.cos(5π+α)

sin(π+α)=-sina=-1/3 sina=1/3 cosa=±2√2/3
cos(5π+α)=-cosa=±2√2/3