(2cos10°-sin20°）/cos20°化简求值
问题描述：
(2cos10°-sin20°）/cos20°化简求值
答
=[2cos(30-20)-sin20]/cos20
=(2cos30cos20+2sin30sin20-sin20]/cos20
=(2*根号3/2*cos20+2*1/2sin20-sin20)/cos20
=(根号3cos20+sin20-sin20)/cos20
=根号3cos20/cos20
=根号3