Question

How do you graph a circle x^2 + y^2=25 and the line is given y=2

Answer 1

$\bf \textit{equation of a circle}\\\\ (x-{{ h}})^2+(y-{{ k}})^2={{ r}}^2 \qquad \begin{array}{lllll} center\ (&{{ h}},&{{ k}})\qquad radius=&{{ r}} \end{array}\\\\ -------------------------------\\\\ x^2+y^2=25\implies (x-0)^2+(y-0)^2=5^2$

so notice above, the circle is centered at h,k or 0,0, the origin, and has a ratio of 5.

and y = 2, is just a horizontal line, check the picture below.