How do I find the inverse tangent of a line?

I've got a line (x1,y1) an开发者_StackOverflow社区d (x2,y2). I'd like to use tan inverse to find the angle of that line, how would I do so in java?

I'd like to see what angle the line makes in relation to x1,y1

---

You need

Math.toDegrees(Math.atan((y2-y1)/(x2-x1)))

Do notice exception when x1=x2.

---

Use the Math.atan2 function. It is like arctan but knows about x and y coordinates, so it can handles lines that are horizontal, vertical, or pointing in other directions -- arctan's range of -pi/2 through pi/2 will not give the correct answer for some lines.

---

The atan2 function helps solve this problem while avoiding boundary conditions such as division by zero.

Math.atan2(y2-y1, x2-x1)

---

This post Angle between 2 points has an example using atan().