题目
4cos50°-tan40°=______.
提问时间:2021-04-04
答案
4cos50°-tan40°=4sin40°-tan40°
=
=
=
=
4sin40°cos40°−sin40° |
cos40° |
=
2sin80°−sin(30°+10°) |
cos40° |
=
2cos10°−
|