Question

求计算题：cos315°+sin(-30°)+sin135°+cos480°

Answer 1

=cos(360°-45°)+sin(-30°)+sin(180°-45°)+cos(360°+120°)

=cos(-45°)+sin(-30°)-sin(-45°)+cos120°

=cos45°-sin30°+sin45°+cos(180°-60°)

=cos45°-sin30°+sin45°-cos60°

结果是根号2减1