Question

A Regular polygon of n sides is constructed, then find the total no. of diagonals of the polygon.​

Answer 1

$\huge\mathfrak{solution}$

The number of lines each joining 2 out of the n points is :

$n_{c_{2}}$

But these will include the n sides of the polygon .

So,

Number of diagonals

= no. of lines -no. of side

$= n_{c_{2}} - n$

Solution refer to the attachment