cos2165°+sin215°+cos105°cos15°的值等于A. B. C. D.
cos2165°+sin215°+cos105°cos15°的值等于( )
A.
B.
C.
D. 
在线课程
解析:原式=cos2(180°-15°)+sin215°+cos(90°+15°)cos15°
=cos215°+sin215°-sin15°cos15°
=1-sin30°=.
答案:D
