Find the standard form for the equation of a circle
(x-h)^2 + (y-k)^2 = r^2 with a diameter that has endpoints (-1, 4) and (5, 0).

i just need to find r

Question

Find the standard form for the equation of a circle
(x-h)^2 + (y-k)^2 = r^2 with a diameter that has endpoints (-1, 4) and (5, 0). 

i just need to find r

anonymous · Answer

if you find the length of  a diameter and divide it by 2 .you will find it's radius .

anonymous · Answer

well i got (2,2) for h,k do i just plug in the equation to find r?

anonymous · Answer

well.you only want to find r so you should find the  length of a diameter with using this formula:
$$D=\sqrt{(y _{2}-y _{1})^2+(x _{2}-x _{1})^2}$$

anonymous · Answer

so i got sqrt 37

anonymous · Answer

are you sure?
(0-4)^2+(5-(-1))^2=16+36=52
D=sqrt52=sqrt4*13=2*(sqrt13)

anonymous · Answer

opps i switched them