2sin20°+cos10°+tan20°sin10°=_．
问题描述：
2sin20°+cos10°+tan20°sin10°=______．
答
2sin20°+cos10°+tan20°sin10°
=2sin20°+cos10°+
sin20°sin10° cos20°
=
2sin20°cos20°+cos10°cos20°+sin20°cos10° cos20°
=
sin40°+cos10° cos20°
=
cos50°+cos10° cos20°
=
2cos30°•cos20° cos20°
=2cos30°
=
．
3
故答案为：
．
3