Question

How many triangles can be formed by joining the vertices of a hexagon ?

• A. $31$
• B. $25$
• C. $20$
• D. $60$

Answer 1

Answer: (C)

$20$

There are 6 vertices of a hexagon. One triangle is formed by selecting a group of 3 vertices from given 6 vertices. This can be done in $6_{C_3}$ ways.

Therefore, Number of triangles = $6_{C_3}=\frac{6!}{3!3!}=20$.