若cos(a+π/6)等于3/5,则cos(a)的值为?

问题描述:

若cos(a+π/6)等于3/5,则cos(a)的值为?

(a+π/6)=53.1301023541°
a=53.1301023541°-30°=23.1301023541°
cos(a)=0.9196