The circle C1 C_1\,C1 has equation x2+y2−4x+6y−12=0x^2+y^2-4x+6y-12=0x2+y2−4x+6y−12=0.
The circle C2 C_2\,C2 has equation (x−8)2+(y+3)2=k2(x-8)^2+(y+3)^2=k^2(x−8)2+(y+3)2=k2, where k>0k>0k>0.
Find all values of k k\,k for which the circles touch.
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.