Is there a way , I can get my plugin to read the server.properties and and find the spawn protection radius , and send a command while player exit that radious or re enter it! Ive be stuff for so long on this... Xode for this is very much needed and would help!

In player move event, compare to and from. If the distance from spawn is longer than the radius in to but shorter than radius in from, send the message.

Use the Pythagoras's theorem a²+b²=c². Though, PocketMine has implemented the theorem in the Vector3->diatance() and diatanceSquared() function.

This is not algebra... This is very basic geometry. It is supposed to be taught at 13 years old in Hong Kong, but I understood it at 9 years old already. It is simply too simple. If you can't even understand that, give up to advanced programming.

Isn't it related something to triangles? I remember learning about it in school, but didn't pay much attention to it.

And what do two right-angled triangles make? A rectangle. What is the length of the diagonal of the rectangle? The hypotenuse of a triangle. What is it? The distance from one point to another point in coordinate geometry.