What is the lenght from the center of a circle to the outside

The line from the center of the circle to the outside is called the radius

Assuming that the question you're asking is:
What is the length from the center of a circle to the outside called?

It's called a radius

Center to outside = RADIUS
Straight line from one side to another = either arch or DIAMETER
Distance around the circle = CIRCUMFERENCE

Hope that helps and correct me if I'm wrong!