Question

What is the equation of the circle with center (1, 1) that passes through the point (−3, 4)?

Answer 1

Answer:  (x - 1)² + (y - 1)² = 25

Step-by-step explanation:

The formula for a circle is     (x - h)² + (y - k)² = r²     where

• (h, k) is the center
• r is the radius

Typically, you are given the center and the radius.  In this problem, you are given (x, y) so you must plug that into the equation to find r².

Given: (x, y) = (-3, 4)   and   (h, k) = (1, 1)

                       (-3 - 1)² + (4 - 1)² = r²

                         (-4)²    +   (3)²   = r²

                          16      +    9     = r²

                                  25         = r²

Next, input (h, k) and r² into the equation

                  (x - 1)² + (y - 1)² = 25