Question

How many diagonals does a triangle have?

• A. $0$
• B. $1$
• C. $2$
• D. $3$

Answer 1

The correct option is A $0$

The number of diagonals of an $n$ sided polygon is given by $D_n=\frac{n(n-3)}{2}$ .

A triangle has $3$ sides. So, $n=3$.

$\therefore D_3=\frac{3(3-3)}{2}=0$