Question

A circle with center (-1, 2) passes through point (2, -2). Which is true?

-The radius is sqr root of 5
-The diameter is 10
-The equation is (x+1)^2+(y-2)^2=10
-The circumfrence is 25pi

Answer 1

You can use the distance formula to find the radius. That will help tremendously here. Take the distance from the center to the point on the circle. Can you do that or do you need help with that?

Answer 2

If u find the distance b/w the centre and the given point u get the radius = 5 units
Now u know the centre and the radius so equation becomes (x+1)^2 + (y-2)^2 = 25

Answer 3

I need help

Answer 4

\[d = \sqrt{(x _{1} - x _{2})^{2} + (y _{1} - y _{2})^{2}}\]

Answer 5

alright. let me work it out real quick

Answer 6

Ya @tcarroll010 this is the distance formula use the given points n u get radius = 5 units
N then u form the equation n u get it what i hv already stated

Answer 7

Your x1 is from the point for the center just as your y1 is:

x1 = -1 y1 = 2

So, the point on the circle is the "second point"

x2 = 2 y2 = -2

So, you can make the substitutions to get the "d" or distance which will be the radius.

Answer 8

so the diameter is ten

Answer 9

Good job! you got it!

Answer 10

:)

Answer 11

thank you!

Answer 12

ya @ejune420

Answer 13

Nicely done, and give yourself a pat on the back, @ejune420

Answer 14

yw

Answer 15

anytime!

Answer 16

Good luck in all of your studies and thx for the recognition! @ejune420

Answer 17

you're welcome :)