Graphing Circles

<p><a target="_blank" href="https://www.prepswift.com/quizzes/quiz/prepswift-graphing-circles">Graphing Circles Exercise</a></p><p><span style="color:#27ae60;">Graphic Circles</span> is pretty straightforward if your equation is in the general format, as seen below:</p> <p>$$r^2 = (x-h)^2 + (y-k)^2$$</p> <p>Where:</p> <ul> <li>$(h,k)$ is the circle&#39;s center</li> <li>$r$ is the radius of the circle</li> <li>$(x,y)$ represent poins on the circle</li> </ul> <p><strong><span style="color:#8e44ad;">Example</span></strong></p> <p>$$16 = (x-5)^2 + (y+2)$$</p> <p>The radius of the circle above is $4$ and the center is $(5, -2)$.</p> <p><strong><span style="color:#8e44ad;">What if it&#39;s not in the general format?</span></strong></p> <p>You likely have to complete the square (maybe even twice) to get it into the general format. See below:</p> <p>$$3 = x^2 +4x + y^2 -6y$$</p> <p>We have to complete the square twice, once for the $x$ and once for the $y$.</p> <p>$$3 + 4 + 9 = (x^2 +4x +4) + (y^2 -6y + 9)$$</p> <p>$$16 = (x+2)^2 + (y-3)^2$$</p> <p>Amazeballs.</p>