Question

Write the standard equation of a circle with center (0, 3) and radius 7.

Answer 1

Circle equation:
$(x - xo)^{2} + (y - yo)^{2} = {r}^{2}$

Center (0, 3)
Xo = 0
Yo = 3

Radius: 7
r = 7

So:

$(x - 0)^{2} + (y - 3)^{2} = {7}^{2}$
${x}^{2} + (y - 3)^{2} = 49$

Answer: x^2 + (y - 3)^2 = 49

Answer 2

$\text{The standard form of the circle:}\\\\(x-h)^2+(y-k)^2=r^2\\\\\text{h and k are the x and y coordinates of the center}\\\\\text{We have:}\\\\\text{the center}\ (0;\ 3)\to h=0;\ k=3\\\\\text{the radius}\ r=7\\\\\text{substitute:}\\\\(x-0)^2+(y-3)^2=7^2\\\\x^2+(y-3)^2=49$