(2cos50°+sin20°)/(2sin10°+√3*sin20°)求值
问题描述:
(2cos50°+sin20°)/(2sin10°+√3*sin20°)求值
答
2cos50 = 2cos(30+20) = 2cos30cos20 - 2sin30sin20 = √3cos20 - sin20分子 = √3cos202sin10 = 2sin(30-20) = 2sin30cos20 - 2sin20cos30 = cos20 - √3sin20分母 = cos20=>原式 = √3