问题
填空题
|
答案
=2cos10°-sin20° 4sin70°
=2cos10°-sin(30°-10°) 4sin70° 2cos10°-
cos10°+1 2
sin10°3 2 4sin70°
=
=
cos10°+3 2
sin10°3 2 4sin70°
=
(3
cos10°+3 2
sin10°)1 2 4sin70°
=
sin70°3 4sin70°
，3 4
故答案为
．3 4