sin120°+cos750°+sin(-690°)cos(-660°)+tan675°+cot765°-tan1020°+cot(-1230°)等于?
问题描述：
sin120°+cos750°+sin(-690°)cos(-660°)+tan675°+cot765°-tan1020°+cot(-1230°)等于?
答
sin120°=cos30°cos750°=cos30°sin(-690°)=sin30°cos(-660°)=cos60°tan675°=tan45°cot765°=cot45°tan1020°=-tan60°cot(-1230°)=cot30°sin120°+cos750°+sin(-690°)cos(-660°)+tan675°+cot765°-t...