Question

How many interior angles are there in a closed shape of 'n' number of straight edges?

number of interior angles

Answer 1

Angles formed by adjacent sides of the polygon at the vertices are called interior angles.

A closed shape of 'n' number of straight edges is a polygon of n sides.
It will have 'n' number of pairs of adjacent sides.

Hence, 'n' number of interior angles are formed.

For, example, a pentagon has $5$ interior angles.