Step-by-step explanation:
We are given the following details:
A square and a regular octagon have the same perimeter. However the sides are not given. Let us assign a variable to the sides of the octagon. One side of the octagon would be represented by letter x.
Note that it is a regular octagon which means all eight sides have the same length. Next we are told that one side of the square is 7 feet longer than one side of the octagon. This means one side of the square would be 7 + x. Note that a square too has all four sides with equal length.
Therefore we would hav e the following;
![\begin{gathered} Octagon=x \\ Square=7+x \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/xrbzj73slzn0gp3hu830wysv23bh6xzu0w.png)
Next we are told the two figures have the same perimeter.
The perimeter of an octagon is;
![\begin{gathered} Octagon: \\ Perimeter=8x \\ Where: \\ x=length\text{ of one side} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/42evawnurwkrhfaphn2gzi30ro22q6d805.png)
For a square we have;
![\begin{gathered} Square: \\ Perimeter=4x \\ Where: \\ x=length\text{ of one side} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/2ge0dgoasqv1gfel6s1z8gz41ytl91comk.png)
Note however that the length of the square in this instance is (7 + x), hence we can re-write this equation as;
![\begin{gathered} Square: \\ Perimeter=4\left(7+x\right) \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/sb1dzm5wte9zpzkuz397k7zu8e3q3i5qqp.png)
Since the perimeters for both are equal, we can equate both equations and we'll have;
![8x=4\left(7+x\right)](https://img.qammunity.org/2023/formulas/mathematics/college/hot21x6fnzf4i9sqqgp8f89jap7uh807gw.png)
We can now solve for the variable x;
![8x=4\left(7+x\right)](https://img.qammunity.org/2023/formulas/mathematics/college/hot21x6fnzf4i9sqqgp8f89jap7uh807gw.png)
![8x=28+4x](https://img.qammunity.org/2023/formulas/mathematics/college/i6dxmubir7r5qnctkn1hf15ujqm2w2l70w.png)
Combine like terms;
![8x-4x=28](https://img.qammunity.org/2023/formulas/mathematics/college/naa3vbbtugu05he22c77uwy5qn8nktvk82.png)
![4x=28](https://img.qammunity.org/2023/formulas/mathematics/high-school/qwczn4imn71ywcbuj4kq79dtucdv3pnx85.png)
Divide both sides by 4;
![\begin{gathered} (4x)/(4)=(28)/(4) \\ x=7 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/98gcgloglcmgluwc2lj2irut0qk9e2oa4a.png)
This means the length of a side of the octagon is 7 feet, while the length of a side of the square is 14 feet (7 + 7).
ANSWER:
![\begin{gathered} Octagon=7ft \\ Square=14ft \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/altav3t346ywb7dxxqxftv5fbkj6cuy3xh.png)