Question

Circle P has a radius of 8 units with center P at (2, -1).Which equation defines circle P?
a. (x + 2)2 + (y – 1)2 = 64
b.(x – 2)2 + (y + 1)2 = 64
c.(x – 2)2 + (y + 1)2 = 8
d. (x + 2)2 + (y – 1)2 = 8

Answer 1

The trick here is that if the center is at x = 2, the equation will have (x-2)^2

Answer 2

\[(x - h)^2 + (y - k)^2 = r^2\]where
r=radius
h=x
k=y

Answer 3

And of course the other thing is that as Romeo says, you need r^2 on the rhs.

Answer 4

So it's b or c.

Answer 5

ok

Answer 6

no you can only have one answer.

Answer 7

you square the radius and you get 64

Answer 8

so it's c?

Answer 9

what does c have in the end?

Answer 10

8^2 is equal to 64.... but it's missing the ^2.

Answer 11

If the radius is 8 then you will have 64 on the rhs.

Answer 12

so we need a 64 in the end.

Answer 13

we can say that c and d are not the answer because of this

Answer 14

ok. thank you so much! Sometimes, it's hard to get some concepts trough my head. So, it's b

Answer 15

Thanks!