Example Find the equation of a circle with radius 3 units and centre (0, 0) The radius, r = 3 and r 2 = 9, so the equation of the circle is x 2 + y 2 = 9 ...

GCSE Edexcel Other graphs - Edexcel The equation of the tangent to a circle - Higher The most commonly occurring graphs are quadratic, cubic, reciprocal, exponential and circle graphs.