Question

A circle whose center is at (1, -3) passes through (7, 5). What is the length of the radius of the circle?

Answer 1

Do you know what the distance formula is?

Answer 2

\[r ^{2} = [5^{2}-(-3)^{2}] + [7^{2}-1^{2}]\]
so r = 8 units

Answer 3

not quite
\[r^{2} = (7-1)^{2} + (5-(-3))^{2}\]
r = 10