🛠️ JEE➗ Maths

The number of triangles whose vertices are at the vertices of a regular octagon but none of whose sides is a side of the…

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The number of triangles whose vertices are at the vertices of a regular octagon but none of whose sides is a side of the octagon is

[JEE Main 2024, 06 Apr (Shift 1)]

a

24

b

56

c

16

d

48

✓ Correct answer: c)

16

Explanation

\(∵\) No. of triangles having no side common with an sided polygon

\(=\frac{{}^{n}{C}_{1}{.}^{n−4}{C}_{2}}{3}\)

\(=\frac{{}^{8}{C}_{1}{.}^{4}{C}_{2}}{3}=16\)

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