欢迎来到想听!
问题描述:
cos50°(tan60°-tan10°)=?
cos50°(tan60°-tan10°)=cos50°[(sin60°cos10°-sin10°cos60°)/cos60°cos10°]=cos50°(sin50°/cos60°cos10°)=sin100°/(2cos60°cos10°)=sin(90°+10°)/cos10°=cos10°/cos10°=1