Two circular gears of radius 4 and 2 units are mounted so that their centers are 6 units apart. How many common tangents do they have?
Show answer & explanation
Correct answer: D
Explanation
Given:
Radius of the first circle = 4
Radius of the second circle = 2
Distance between the centers = 6
By the formula:
If d = r₁ + r₂, then the circles touch externally and the common tangents = 3
r₁ + r₂ = 4 + 2 = 6
d = 6
Hence, the two circles touch externally
Common tangents = 3