Sat question: a circle in the xy-plane has a diameter with endpoints (-1,-3) and (7,3). if the point (0,b) lies on the circle and b > 0, what is the value of b

1) use the distance formula to find that the radius (r) of the circle = 5

2) use the midpoint formula to find that the center of the circle (h,k) = (3, 0)

3) Now use the formula of a circle and input the (h,k) and r to create:

(x - 3)² + (y - 0)² = 5² → (x - 3)² + y² = 25

4) input the "x" value given in the question (x = 0) and solve for "y":

(0 - 3)² + y² = 25 → 9 + y² = 25 → y² = 16 → y = +/- 4

Since the question states that "b" must be positive, you can disregard the -4.

b = 4