Question

Вычислите 1) sin 765 ; 2)cos 19п/6 ; 3) sin 7п/3 ; 4) tg 5п/12

Answer 1

1) sin765 = sin45 = $\frac{ \sqrt{2} }{2}$
2) cos19p/6 = A = 19p/6 - 2p => A = 7p/6 => cos (7p/6) => $- \frac{ \sqrt{3} }{2}$ 
3)sin(7p/3) => A=7p/3 - 2p => p/3 => $\frac{ \sqrt{3} }{2}$