求sin30cos15 cos30sin15 2. 求√3cosπ/12-sinπ

解析:cos 15° cos 30° -cos 75° cos 60° =cos

求sin15° cos15° 详细过程

sin30°·cos30° cos60°·sin45等于多少啊?

sin13°cos17°-cos13sin17=1/2 sin140°cos20 sin50sin