1 、( 1)-cos 30(2)-sin 83 42 '(3)cosπ/6(4)sinπ/3(5)-cos 2π/9(6)-cos 75 34 '

(7)-tan87 36'(8)-tanπ/6

2、( 1)√2/2(2)-0.7 193(3)-0.0 15 1(4)0.6639(5)-0.9964(6)-√3/2

3 、( 1)0(2)-cos？ a

4 、( 1)sin(360-a)= sin(-a+360)= sin(-a)=-Sina

(2)cos(360-a)= cos(-a+360)= cos(-a)= cosa

(3)tan(360-a)= tan(-a+360)= tan(-a)=-tana