The number of common tangents to the circles x2 + y2 = 4, x2 + y2 - 4x + 2y - 4 = 0 is

Question

The number of common tangents to the circles x2 + y2 = 4, x2 + y2 - 4x + 2y - 4 = 0 is (A) 1 (B) 2 (C) 3 (D) 4

Tardigrade Admin · Accepted Answer

c1 = (0, 0), c2 = (2, -1), r1 = 2 and r2 = 3 |c1 c2| = √5 r1 + r2 > |c1 c2| So, there are two common tangents

Q. The number of common tangents to the circles $x^{2} + y^{2} = 4, x^{2} + y^{2} - 4 x + 2 y - 4 = 0$ is