问题
选择题
sin7°cos37°-sin83°cos53°的值为( )
|
答案
sin7°cos37°-sin83°cos53°
=cos83°cos37°-sin83°sin37°
=cos(83°+37°)
=cos120°
=-
,1 2
故选A.
sin7°cos37°-sin83°cos53°的值为( )
|
sin7°cos37°-sin83°cos53°
=cos83°cos37°-sin83°sin37°
=cos(83°+37°)
=cos120°
=-
,1 2
故选A.