Question

The radius of the circle whose equation is (x - 3)² + (y + 1)² = 16 is

Answer 1

A circle whose center is located at point (a, b) having a radius of length r has the equation:
(x -a)² + (y -b)² = r²

Therefore the radius = sq root (16) which = 4

Source:
http://www.1728.org/circle.htm

Answer 2

Answer:

The radius of the circle whose equation is (x - 3)² + (y + 1)² = 16 is:

                              4 units.

Step-by-step explanation:

We know that the general equation of a circle with center at (h,k) and radius 'r' is represented by the equation:

       $(x-h)^2+(y-k)^2=r^2$

Here we are given a equation as:

   $(x-3)^2+(y+1)^2=16$

i.e. on comparing the given equation with the general equation we have

h=3 and k= -1

and $r^2=16$

on taking square root we get:

$r=4$

          Hence, the radius of the equation is:

                            4 units