What Are Conic Sections and Circles?
Think of conic sections as the shapes you'd see if you sliced through an ice cream cone with a knife at different angles. Conic sections include circles, parabolas, ellipses, and hyperbolas - each created by changing how the cutting plane intersects the cone.
A circle is simply all the points that are exactly the same distance from a center point. That fixed distance is called the radius (r), and it's the key to writing circle equations.
The standard form of a circle equation is x−h² + y−k² = r², where (h,k) is the center and r is the radius. For example, if your center is at (-4, 5) with radius 4, you get: x+4² + y−5² = 16.
Pro Tip: Notice how x−(−4) becomes x+4 - the signs can be tricky, so double-check your work!