the unit circle has center â–Ľ left parenthesis 1 comma 1 right parenthesis left parenthesis negative 1 comma negative 1 right parenthesis left parenthesis 0 comma 0 right parenthesis and radius â–Ľ 1. negative 1. startroot 2 endroot . the equation of the unit circle is â–Ľ y equals mx plus b. x squared plus y squared equals 1. y equals ax squared .