Question

Question 2
The number of diagonals in a septagon is
a) 21
b) 42
c) 7
d) 14

Answer 1

A diagonal is a line segment joining two opposite corners of a polygon.

Number of diagonals in a polygon =$\frac{n(n-3)}{2}$
A septagon is a polygon having seven sides.
i.e. n=7
$\therefore$ Number of diagonals in a septagon = $\frac{7(7-3)}{2}$ =$\frac{7\times 4}{2}$ = 14