cos43°cos77°+sin43°cos167°的值为(  ) A.1 B.12 C.[−12,12] D.12

问题描述:

cos43°cos77°+sin43°cos167°的值为(  )
A. 1
B.

1
2

C. [−
1
2
1
2
]

D.
1
2

cos43°cos77°+sin43°cos167°
=cos43°cos77°-sin43°sin77°
=cos120°
=-

1
2

故选:D.