Question

Please help! I only have about 20 minutes for this problem!
A circle has its center at (2, -4) and a radius of 6 units. What is the equation of the circle?

Answer 1

Do you know how to form an equation for a circle?

Answer 2

Not really, I didn't understand that part in my math lesson quite well. It's the only thing I'm struggling with.

Answer 3

Why do you only have 20 minutes for this question?

Answer 4

I'm going somewhere in 20 minutes but this was a last minute thing. :/

Answer 5

What is the (h,k) form of the equation of a circle?

Answer 6

The circle's center is not at the origin so we will be using the h, k equation.

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

You just . . . fill it in. This is really all you need to know. If the center is at the origin just use:

\[x^2 + y^2 = r^2\]

Answer 7

You fill in for h and k, not for x and y.

Answer 8

Remember to alternate the signs when necessary!

Answer 9

(x - h)^2 + (y - k)^2 = r^2
(h, k) = center and r = radius
so for when its center is at (2, -4) and it has a radius of 6
plug in h=2 , k=-4 , and r=6 into the circle equation ?? That correct?

Answer 10

yeah

Answer 11

Remember that inputting negatives will switch the - to a +