Two circular water tanks have radii of 5 units and 3 units, respectively. The distance between their centers is 13 units. A direct common tangent is laid to pass by both tanks without crossing through them. What is the length of this direct common tangent?
Show answer & explanation
Correct answer: C
Explanation
Given:
r₁ = 5
r₂ = 3
Distance between centers (d) = 13
Formula:
Length of direct common tangent
L = √(d² − (r₁ − r₂)²)
L = √(13² − (5 − 3)²)
= √(169 − 4)
= √165 = 12.85 units