化简sin210°tan(-120°)+cos(-240°)tan420°

问题描述:

化简sin210°tan(-120°)+cos(-240°)tan420°

=-sin30tan60-cos60tan60
=-(cos60tan60)*2
=-2sin60
=-根号3=-sin30tan60-cos60tan60=-(cos60tan60)*2这个感觉写的不太对sin30=cos60