Question

The points ​(​-2,​-1) and ​(6​,​3) are the endpoints of the diameter of a circle. Find the length of the radius of the circle.

Answer 1

Using the distance formula, the diameter has a length of

$\sqrt{(-2-6)^2 + (-1-3)^2}=4\sqrt{5}$

The radius is half the diameter, so the answer is

$\frac{4\sqrt{5}}{2}=\boxed{2\sqrt{5}}$