Hello Sabrina,
The standard form for a circle is (x - h)2 + (y - k)2 = r2, where the center is (h, k).
The center of the circle will be the midpoint of the points given. That is,
h = (-8 + 8) / 2 = 0 and
k = (7 + 3) / 2 = 5.
Now, the x and y in the equation represent points ON the circle, so you can pick either of the given points. I am going to use (8, 3)
→ (8 - 0)2 + (3 - 5)2 = r2, from which you can solve for r2,
→ 64 + 4 = r2
→ r2 = 68
Now just plug in the h, k, and r2
→ (x - 0)2 + (y - 5)2 = 68
→ x2 + (y - 5)2 = 68.
Thank you for the question, and have a great day!
Michael E.