circle C,centre at the point A (5,0) has equation of x^2+y^2-10x+9=0. find radius of C

Question

i already worked out the coordinate A but i dont know how to find the radius.

 

could you explain it as clearly as you can

Answer 1

If you have worked out point A (5,0) then you must have gotten to this equation:

(x-5)^2 + y^2= 16 from this we can see that x must be 5 and y must be 0. Now to find the radius all you have to do is square root 16 which will give you 4! This is the radius.