(cosx)∧2+cos(x+120°)∧2+cos(x+240°)∧2的值为

问题描述:

(cosx)∧2+cos(x+120°)∧2+cos(x+240°)∧2的值为

cos(x+120°)∧2+cos(x+240°)∧2
化成cos(x-60°)∧2+cos(x+60°)∧2
再拆开
=1.5