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

Decagon.

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 $\left(n-2\right)180$.

The number of sides in a Decagon is 10.

Therefore, the value of$n$ is 10.

By using the theorem for the sum of interior angles for convex polygon, the sum of the interior angles for the polygon having 10 sides is given by:

$$\begin{gathered} \left(10-2\right)180=8\times 180 \\ =1440 \end{gathered}$$

Therefore, the sum of interior angles for the Decagon is $1440°$.

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 Decagon is 10.

Therefore, the value of$n$ is 10.

By using the theorem for the sum of exterior angles for convex polygon, the sum of the exterior angles for the polygon having 10 sides is $360°$.

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