这俩道化简题怎么做？？？

1:sin(-1071°)·sin99°+sin(-171°)·sin(-261°)
=sin(360*3-1071)*sin99+(-sin171)*sin(360-261)
=sin9sin99-sin171sin99
=sin9sin99-sin(180-171)sin99
=sin9sin99-sin9sin99
=0

2:已知tana=2
tana=sina/cosa=2
sina=2cosa
(sina+cosa)/(sina-cosa)
=(2cosa+cosa)/(2cosa-cosa)
=3cosa/cosa
=3

（1）sin(-1071°）·sin99°+sin(-171°)·sin(-261°)
=sin(-1071°+1080°）·sin99°-sin(-171°+180°)·sin(-261°+360°)
=sin9°·sin99°-sin9°·sin99°
=0

(2)(sinA+cosA)/(sinA-cosA)
=(tanA+1)/(tanA-1)[分式上下同除以cosA]
=（2+1）/(2-1)
=3

第一个是积化和差公式，把角度都化成<90度的
第二个也是公式，具体的忘了