Question

A diameter of a circle has endpoints of
(
−
5
,
6
)
and
(
−
5
,
−
2
)
. What is the equation of this circle?
A.
(
x
+
5
)
2
+
(
y
−
2
)
2
=
16

B.
(
x
−
5
)
2
+
(
y
+
2
)
2
=
4

C.
(
x
+
5
)
2
+
(
y
−
2
)
2
=
4

D.
(
x
+
5
)
2
+
(
y
−
2
)
2
=
64

Answer 1

Midpoint (center) = ((-5 + -5)/2, (6 + -2)/2) = (-5, 2).
Diameter length = |6 - (-2)| = 8, so radius = 4 and r^2 = 16.

Equation: (x + 5)^2 + (y - 2)^2 = 16. (Answer A)