Question

A circle is centered at the point (-3, 2) and passes through the point (1, 5). The radius of the circle is ___ units. The point (-7, ___) lies on this circle.

Answer 1

Use the distance formula to find the radius


(x1,y1) = (-3,2)
x1 = -3
y1 = 2


(x2,y2) = (1,5)
x2 = 1
y2 = 5

\[\Large d = \sqrt{(x_1-x_2)^2+(y_1-y_2)^2}\]
\[\Large d = \sqrt{(-3-1)^2+(2-5)^2}\]
I'll let you finish

Answer 2

so the radius is -8? or -64?

Answer 3

the radius will be some positive number

Answer 4

\[\Large d = \sqrt{(x_1-x_2)^2+(y_1-y_2)^2}\]
\[\Large d = \sqrt{(-3-1)^2+(2-5)^2}\]
\[\Large d = \sqrt{(-4)^2+(-3)^2}\]
\[\Large d = \sqrt{16+9}\]
\[\Large d = ???\]

Answer 5

5?

Answer 6

d = 5, yes

Answer 7

the distance is 5, so the radius is r = 5

Answer 8

then would the point lie on -7, -2?

Answer 9

there are two points on the red circle such that the x coord is -7

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Answer 10

`then would the point lie on -7, -2?`
no, not correct

Answer 11

so it's either -7, -1 or -7, 5?

Answer 12

use parenthesis whenever talking about ordered pairs

yes (-7,-1) or (-7,5)

Answer 13

Yay! I think I'm finally starting to understand this stuff more, thank you for helping me out so much.

Answer 14

you're welcome