求值:2sin50°+cos10°(1+根号3tan10°)/根号下1+2sin50°cos50°
问题描述：
求值:2sin50°+cos10°(1+根号3tan10°)/根号下1+2sin50°cos50°
答
2sin50°+cos10°(1+根号3tan10°)/根号下1+2sin50°cos50°
=(2sin50°+cos10°(1+√3*tan10°))/√(sin^2 50°+2sin50°cos50°+cos^2 50°)
=(2sin50°+cos10°+√3sin10°)/√√(sin50°+cos50°)^2
=(2sin50°+2sin(10°+30°))/(sin50°+cos50°)
=2(sin50°+sin40°)/(sin50°+cos50°)
=2(sin50°+cos50°)/(sin50°+cos50°)
=22(sin50°+sin40°)/(sin50°+cos50°)这一步怎么来的？没看懂！cos10°+√3sin10°=2(1/2cos10°+√3/2sin10°)=2(sin30°cos10°+cos30°sin10°)=2sin(30°+10°)=2sin40°