Question

The point (-9, -7) is on a circle with center (8, 4). Write the standard equation of the circle

Answer 1

The square of the radius is found using the Pythagorean theorem.
.. (8 -(-9))^2 +(4 -(-7))^2 = r^2
.. 17^2 +11^2 = r^2
.. 289 +121 = r^2 = 410

So, the equation of the circle can be written as
.. (x -8)^2 +(y -4)^2 = 410