Two circles C1 and C2 have radii 5 and 3 units, and their centers are 13 units apart. Then the number of common tangents they have is:
Show answer & explanation
Correct answer: D
Explanation
Given:
Radius of circle C₁ = 5
Radius of circle C₂ = 3
Distance between centers = 13
By formula:
If d > r₁ + r₂, then common tangents = 4
r₁ + r₂ = 5 + 3 = 8
d = 13
Since 13 > 8
Hence, the two circles are different.
Number of common tangents = 4