A "radian" is an alternative way of measuring an angle. It was developed for a particular purpose that you will soon see is quite useful. So what is a radian?
If you place the radius of a circle on the outside of a circle, the central angle created with the arc is called "1 radian." For each radius place on the outside of the circle you increase the angle of the central angle in radians. This is an alternative way of measuring an angle using the radius of a circle. The unit of measurement is called a "radian."
It appears that the angle in radians around the circle is a bit more than 6 radians.