This means that, using Pythagoras’ theorem, the equation of a circle with radius r and centre (0, 0) is given by the formula \(x^2 + y^2 = r^2\). Example Find the equation of a circle with ...

Draw a diagram to show the circle and the tangent at the point (2, 4) labelling this P. Draw the radius from the centre of the circle to P. The tangent will have an equation in the form \(y = mx + c\) ...