Coordinate Geometry
Circles
MMTS_Full_Test_22
Grade 12
Question:
The number of common tangents to circles $x^2+y^2-4x-6y-12=0$ and $x^2+y^2+6x+18y+26=0$ is
Step-by-Step Solution
Key Concept: Find centres and radii; check distance between centres vs sum/difference of radii
$|C_1C_2|=r_1+r_2=13$: exactly externally tangent. 3 common tangents.
Correct Answer: 2