Question

化简｛Cos（1800+α）sin(-α)｝除以tan(-α-180o)

Answer 1

cos(180°+α)*sin(-α)/tan(-α-180°)

=-cosα*(-sinα)/tan(-α)

=sinα*cosα/(-tanα)

=sinα*cosα*cosα/(-sinα)

=-(cosα)^2