External ray

Have you ever seen a ray of sunshine that shines into your room through a window? An external ray is just like that, but instead of sunshine, it's a line that starts outside a shape and enters (or tries to enter) the shape through one of its corners.

Imagine you have a shape, like a circle or a square. Now imagine drawing a line from a point outside the shape, towards the shape. This is an external ray. It's called external because it starts outside the shape and doesn't go inside. The point where the ray touches the shape is called the endpoint.

Sometimes, the external ray will bounce off the shape and go in a different direction. This is called reflection. The angle at which the ray bounces off is called the angle of reflection, and it's equal to the angle at which the ray hit the shape.

External rays can be used to study and understand the shape they are coming from. Mathematicians use external rays to create a map of the shape and study properties like its angles and sides. They can even use external rays to figure out what the shape would look like from different angles!

So, there you have it, External rays are just lines that start outside a shape and try to enter through one of its corners. They can bounce off the shape like a ray of sunshine bounces off a mirror, and they help us understand the shape better.