sin (20)^circ cos (10)^circ -cos (160)^circ sin (10)^circ =-|||-()-|||-

(湘教版第二册P1122习题3.4第2题,改-|||-编)(数学运算)复数 =(cos (25)^circ +-|||-sin (25)^circ )(cos

dfrac (sqrt {3)}(2)sin (15)^circ +dfrac (1)(2)cos (15)^circ 的值为( )A．dfrac

16.单选题-|||-已知 sin (36.9)^circ =0.6 ,cos (36.9)^circ =0.8 。将复数 =1-|||-angle -(36.

^circ +(25)^circ =-|||-^circ +(81)^circ =-|||-^circ +(140)^circ =-|||-^circ -(25

sin20°cos10°-cos160°sin10°=（ ）A. -$\frac{\sqrt{3}}{2}$B. $\frac{\sqrt{3}}{2}$C.

画下面各角。-|||-^circ -|||-^circ -|||-^circ

2.比较温度的高低。-|||-^circ Cbigcirc (5)^circ C-|||-^circ Cbigcirc -(2)^circ C-|||-^cir

6、已知 =sqrt (xln xsqrt {1-sin x)} ,则 ^circ = .__

^circ -dfrac (4)(2)-|||-:^circ +dfrac ({varphi )^1}(2) D. ^circ -dfrac ({varphi

内容一：求值问题例1：(1)sin20°cos10°-cos160°sin10°=____.(2)cos10°-2cos20°cos10°=____.变式练习：