The lines with equations y=k3x\displaystyle y=\frac{k}{3}xy=3kx and y=−k3x\displaystyle y=-\frac{k}{3}xy=−3kx are tangents to a circle at (3,k)(3,k)(3,k) and (3,−k)(3,-k)(3,−k) respectively, where k k\,k is a non-zero constant.
Find an equation for the circle in terms of kkk.
292 exam-style questions on Edexcel A Level Maths Circles, covering 6.1 Midpoints and Perpendicular Bisectors, 6.2 Equation of a Circle, 6.3 Intersections of Straight Lines and Circles, 6.4 Use Tangent and Chord Properties, and 6.5 Circles and Triangles. Each one has a worked solution and a mark scheme showing where the marks go.