← Back

Bertrand's Paradox

1. Random Endpoints
Two random points on circumference
2. Random Radius
Random point on a radius, perpendicular chord
3. Random Midpoint
Random point in circle as chord midpoint
10
Total chords:0
Longer than triangle side:0
Ratio:-
Expected:1/3

The Paradox

"What is the probability a random chord is longer than the side of an inscribed equilateral triangle?"

The answer depends on what "random" means:

Method 1: P = 1/3
Method 2: P = 1/2
Method 3: P = 1/4

All three are legitimate! "Random" is ambiguous without specifying a distribution.