For each polygon, find (a) the interior angle sum and (b) the exterior angle sum.

Quadrilateral.

The theorem for the sum of interior angles for convex polygon states that the sum of measures of the interior angles of a convex polygon with sides is $\left(\mathit{n}-2\right)180$.

The number of sides in a quadrilateral is 4.

Therefore, the value of$n$ is 4.

By using the theorem for the sum of interior angles for convex polygon, the sum of the interior angles for the polygon having 4 sides is given by:

$$\begin{gathered} \left(4-2\right)180=2\times 180 \\ =360 \end{gathered}$$

Therefore, the sum of interior angles for the quadrilateral is $360°$.

The theorem for the sum of exterior angles for convex polygon states that the sum of measures of the exterior angles of a convex polygon is $360°$.

The number of sides in a quadrilateral is 4.

Therefore, the value of$n$ is 4.

By using the theorem for the sum of exterior angles for convex polygon, the sum of the exterior angles for the polygon having 4 sides is $360°$.

Therefore, the sum of exterior angles of the quadrilateral is $360°$.