The circle C C\,C has centre (5,k)(5, k)(5,k), where k k\,k is a constant. The line y=2x+1y = 2x + 1y=2x+1 is a tangent to the circle CCC, touching C C\,C at the point A(3,7)A(3, 7)A(3,7).
Find an equation for CCC.
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.