If the radius is two. it won't be a unit circle, a unit circle is defined as a circle with radius one.

The unit circle is a circle with its center at the origin and a radius of ' 1 '.

A unit circle is a circle with radius equal to one.

It is unknown who created the unit circle. Pythagoras did a lot of work related to the unit circle. In ancient times, Greek, Indian, and Arabian mathematicians used the unit circle.

A unit circle is not normally called 2 pi. Because the radius length measure of the unit circle is 1 unit, then the circumference of a unit circle is 2*pi, and its area is pi.