化简(1)sin(-1071度).sin99度+sin(-171度).sin(-261度)

2025-12-15 02:51:19
推荐回答(1个)
回答1:

原式=sin(-360*3+9)sin99+sin(-180+9)sin(-360+99)
=sin9sin99+(-sin9)sin99
=sin9sin99-sin9sin99
=0