To calculate the area of the sector you have to use the following formula:
![A_{\text{sector}}=(\theta)/(360º)\cdot\pi r^2](https://img.qammunity.org/2023/formulas/mathematics/college/pjrpbxj7vc5mgr8nyb7gclt5cwsxvle6y8.png)
Where θ represents the measure of the central angle of the sector.
The measure of the central angle is equal to the measure of the intercepted arc, so that θ=80º
So you calculate the area of the sector as follows:
![\begin{gathered} A_{\text{sector}}=(80)/(360)\cdot\pi(4^2) \\ A_{\text{sector}}=(32)/(9)\pi\approx11.17 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/f7px1pywn6ay7vpc1s4w18k9v6qrvtyde8.png)