Write the equation of a circle with center (6,4) that passes through the coordinate (2,1). in your final answer, include all of your calculations.

All points along the circle with be the distance of the radius from the center...so the radius can be found using the Pythagorean Theorem..

r^2=(4-1)^2+(6-2)^2

r^2=9+16

r^2=25

r=5

The equation of the circle can be expressed as:

r^2=(x-h)^2+(y-k)^2 where (h,k) correspond to the center of the circle, (2,1) in this case.

(x-2)^2+(y-1)^2=25

if you wanted it in a more standard form...

(y-1)^2=25-(x-2)^2

(y-1)^2=25-x^2+4x-4

(y-1)^2=-x^2+4x+21

y-1=(-x^2+4x+21)^(1/2)

y=1(+/-)(-x^2+4x+21)^(1/2)