Question

A circle has a center at (-3,-2) and the radius is 10 units, which of the following points would be on the circle

a.(8,4)

b(5,-8)

c(3,6)

d(-5,8)

e(7,8

Answer 1

• b (5,-8)
• c (3,6)

Explanation:

A graph is useful for figuring this out.

_____

Since the radius of the circle is 10, we expect that a point with integer coordinates will be on the circle if its coordinates are 6 and 8* units from the center: (-3±6, -2±8) or (-3±8, -2±6). These define 8 points with integer coordinates, of which two are listed in the answer list: (3, 6) and (5, -8).

__

* The radius will be the hypotenuse of a 3-4-5 right triangle scaled by a factor of 2.