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Fifteen distinct points are randomly placed on the circumference of a circle .. At most how many triangles can be formed using these points?
Question

Fifteen distinct points are randomly placed on the circumference of a circle .. At most how many triangles can be formed using these points?

A.

105

B.

455

C.

2730

D.

30

Correct option is B

Given:
15 distinct points on the circumference of a circle
We are to find the maximum number of triangles that can be formed from these points

Concept Used:
To form a triangle, we need to select 3 non-collinear points.
On a circle, no 3 points are collinear, so every combination of 3 points forms a triangle.
So, this becomes a combinations problem:

Solution:

Number of triangles=(153)=15×14×133×2×1=455\text{Number of triangles} = \binom{15}{3} = \frac{15 \times 14 \times 13}{3 \times 2 \times 1} = 455​​

Correct Option: (B) 455

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