Circles

If the equation is not given in standard form, it will need to be converted to standard form by completing the square. To identify an equation as a circle, it will contain an x² and y² term with equal coefficients. See the following examples:

• -3x² - 3y² + x - y = 5 is a circle.
  
• 3x² - 3y² + x - y = 5 is not a circle.
  
• 3x² + 3y = 5 is not a circle.