分类：教育/科学-学习帮助
问题：一道高中数学题(2cos10°
(2c10°-sin20°)/sin70°=?
回答：解:(2cos10°-sin20°)/sin70°
=(2sin80°°-sin20°)/sin70°
=(sin80°+sin80°-sin20°)/sin70°
=(sin80°+2sin30°cos50°)/sin70°
=(sin80°+cos50°)/sin70°
=(sin80°+cos50°)/sin70°
=(sin80°+sin40°)/cos20°
=(2sin60°cos20°)/cos20°
=√3