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Question: The number of common tangents that can be drawn to the circles x<sup>2</sup>+y<sup>2</sup>–4x-6y-3 =...

The number of common tangents that can be drawn to the circles x2+y2–4x-6y-3 = 0 and x2+y2+2x+2y+1=0 is

A

1

B

2

C

3

D

4

Answer

3

Explanation

Solution

The two circles are

x2+y2-4x-6y-3 = 0 and x2+y2+2x+2y+1 = 0

Centres: C1 ≡(2, 3), C2 ≡(-1, -1)

Radii: r1 = 4 r2 = 1

We have, C1 C2 = 5 = r1 + r2, therefore there are 3 common tangents to the given circles