sin(-1071°)×sin99°+sin(-171°)sin(-261°)
=sin(1080°-1071°)×sin(90°+9°)°+sin(360°-171°)sin(-261°+360°)
=sin9°*cos9°+sin(-9°)*cos9°
=sin9°*cos9°-sin9°*cos9°
=0
sin(-1071度)×sin99度+sin(-171度)sin(-261度)化简
sin(-1071度)×sin99度+sin(-171度)sin(-261度)化简
数学人气:824 ℃时间:2020-02-05 15:14:11
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