The circle C C\,C has centre (5,k)(5, k)(5,k), where k k\,k is a constant.
The line with equation y=2x+1y = 2x + 1y=2x+1 is a tangent to CCC, touching C C\,C at the point A(3,7)A(3, 7)A(3,7).
Find an equation for CCC.
143 exam-style questions on OCR A Level Maths 1.3 Coordinate Geometry in the x-y Plane, covering 1.3.1 Straight lines, 1.3.2 Parallel and perpendicular lines, 1.3.3 Straight line models, 1.3.4 Coordinate geometry of a circle, 1.3.5 Centre and radius by completing the square, 1.3.6 Circle properties, 1.3.7 Parametric equations of curves (A-level only), 1.3.8 Parametric equations in context (A-level only), and 1.3 Coordinate Geometry in the x-y Plane. Each one has a worked solution and a mark scheme showing where the marks go.