The circle C C\,C has equation x2+y2+8x−4y+k=0x^2 + y^2 + 8x - 4y + k = 0x2+y2+8x−4y+k=0 where k k\,k is a constant.
C C\,C passes through the point (1,5)(1, 5)(1,5).
Find the value of kkk.
Find the coordinates of the centre of C C\,C and the exact radius of CCC.
A straight line that passes through the point A(3,7)A(3, 7)A(3,7) is a tangent to C C\,C at the point BBB. Find the exact length ABABAB.
76 exam-style questions on WJEC A Level Maths 1.3 Coordinate geometry in the (x, y) plane, covering 1.3.1 Coordinate geometry in the (x, y) plane, 1.3.2 Coordinate geometry in the (x, y) plane, 1.3.3 Coordinate geometry in the (x, y) plane, and 1.3.4 Coordinate geometry in the (x, y) plane. Each one has a worked solution and a mark scheme showing where the marks go.