tan70con10(根号3tan20-1)

问题描述:

tan70con10(根号3tan20-1)
都是 度
con10应该是cos10

首先化简 根号3tan20-1(根号3sin20 - cos20)/cos20=2[sin20cos30 - cos20sin30]/cos20=-2sin10/cos20然后看整体tan70cos10(根号3tan20-1)= - 2(sin70cos10sin10)/(cos70cos20)=-2 cos10 sin10/sin20=- sin20/sin...