the unit circle has center ▼ 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 ▼ 1. negative 1. startroot 2 endroot . the equation of the unit circle is ▼ y equals mx plus b. x squared plus y squared equals 1. y equals ax squared .