问题 填空题
cos50°(tan10°-
3
)=______.
答案

cos50°(tan10°-

3

=sin40°(

sin10°
cos10°
-
3

=sin40°•

sin10°-
3
cos10°
cos10°

=

2sin40°
cos10°
(sin10°cos60°-sin60°cos10°)

=-

2sin40°sin50°
cos10°

=-

sin80°
cos10°

=-1.

故答案为:-1

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