计算直线夹角

https://blog.csdn.net/chelen_jak/article/details/80518973

计算两条相交线的角度和弧度

Point S1 ;

Point E1;

Point S2 ;

Point E2 ;

var a = Math.Atan2(S1.Y - E1.Y, S1.X - E1.X);

var b = Math.Atan2(S2.Y - E2.Y, S2.X - E2.X);

var c = 180 * (b - a) / Math.PI);