计算1/sin50°+3cos50°=_．
问题描述：
计算
+1 sin50°
=______．
3
cos50°
答
1sin50°+3cos50°=cos50°+3sin50°sin50°cos50°=2(12cos50°+ 32sin50°)sin50°cos50°=2(sin30°cos50°+ cos30°sin50°)sin50°cos50°=2sin(30°+50°)sin50°cos50°=2sin80°sin50°cos5...