Given the following interior angle of a regular polygon:
![120\degree](https://img.qammunity.org/2023/formulas/mathematics/college/920gcet7znyo2cofsoiaeja8nx1p6tnm41.png)
You need to remember that, by definition, a regular polygon is a polygon whose sides have all equal lengths.
Therefore, you can apply the following formula:
Where "n" is the number of sides of the polygon and β is the measure of one interior angle of the polygon.
Knowing that, in this case:
![\beta=120\degree](https://img.qammunity.org/2023/formulas/mathematics/college/38o4dtlz1ohloeml90d6uil469mhv0go0l.png)
Therefore, you can substitute this value into the formula and solve for "n":
![\begin{gathered} 120=((n-2)\cdot180)/(n) \\ \\ 120n=180n-360 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/srkvh8m9htqec2ipqx2wgrhcf9q0w2t6gj.png)
![\begin{gathered} 120n-180n=-360 \\ \\ -60n=-360 \\ \\ \\ n=(-360)/(-60) \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/5i8n50iu4uxfbr2awy4a2bnxh9ee56knz0.png)
![n=6](https://img.qammunity.org/2023/formulas/mathematics/college/o7iwtqrm2mbn6a11qav92k1mbcmfp9jb6e.png)
Hence, the answer is:
![n=6](https://img.qammunity.org/2023/formulas/mathematics/college/o7iwtqrm2mbn6a11qav92k1mbcmfp9jb6e.png)