Pre-Calculus Writing equations of circle in standard form If the equation of a circle is in the standard form, we can easily identify the center of the circle, (h, k), and the radius, r . Note: The radius, r, is always positive. Math made easy by prof D General Mathematics Playlist Statistics and Probability Playlist Pre-Calculus Playlist Calculus Playlist For more updates, you can also follow my Facebook Page: Join this channel to get access to perks: Please don't forget to like, share, and subscribe! Thank You Guys!