用诱导法求下列三角函数值:(1)cos(-17π/4) (2)sin[(-26/3)π]

问题描述:

用诱导法求下列三角函数值:(1)cos(-17π/4) (2)sin[(-26/3)π]

cos(-17π/4)=cos(17π/4)=cos(π/4)=根号2/2
sin(-26π/3)= - sin(26π/3)= -sin(2π/3)=-根号3/2