Question

Find the number of triangles formed in a decagon.

Answer 1

As we know no of side $=10$ (in decagon)

So vertices $=10$

So. no. of triangles $={}^{10}{C}_3=\frac{10\times 3\times 8}{3\times 2\times 1}$

$\therefore$ the number of triangles formed in Hexagon $=120$