A circle has equation (x+k)2+(y−4)2=k2+16(x + k)^2 + (y - 4)^2 = k^2 + 16(x+k)2+(y−4)2=k2+16, where k k\,k is a non-zero constant.
Find, in terms of kkk, the gradient of the tangent to the circle at the origin.
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.