# Thread: How did this happen?

1. ## How did this happen?

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

(x - 5)^2 + (y - 2)^2 = 4^2

If there's a 5 and a 2 to work with, how did 4 come up? I don't understand how to solve these radius distance equations. Can I please get some help on this?

2. Originally Posted by BlueStar
(x - h)^2 + (y - k)^2 = r^2

(x - 5)^2 + (y - 2)^2 = 4^2

If there's a 5 and a 2 to work with, how did 4 come up? I don't understand how to solve these radius distance equations. Can I please get some help on this?
you need to tell us the question for us to help you

3. A swimmer jumps 2 feet north and 5 feet east of the corner of the pool. The ripple effect traveled four feet from the center. Model an equation of a circle for the set of points that could be the center of the cannon ball. The corner is the origin at (0,0), and the center is at (5,2) with a radius of 4 feet. I need to find the standard equation using the distance formula.

4. Originally Posted by BlueStar
A swimmer jumps 2 feet north and 5 feet east of the corner of the pool. The ripple effect traveled four feet from the center. Model an equation of a circle for the set of points that could be the center of the cannon ball. The corner is the origin at (0,0), and the center is at (5,2) with a radius of 4 feet. I need to find the standard equation using the distance formula.
as far as i can see, it seems they just want the equation of the circle that forms the cannon ball. in which case it would be an equation of the form (x - h)^2 + (y - k)^2 = r^2 with center (h,k) and radius = 4, which is the standard form of a circle (or do you want to actually derive this equation using the distance formula?)