Answer:
28 feet
Step-by-step explanation:
We know that the perimeter of a square is
, where l is the length and w is the width.
We also know that the perimeter of a triangle is all of its sides added up.
Since the perimeters will be equal to each other, we can make both of these statements an equation that are equal to each other.
Basically:

We can combine like terms to get a <em>less scary</em><em> </em>equation.

Our goal is to now isolate x so we can find it's value.
Add 2 to both sides:

Subtract 6x from both sides:

Add 10 to both sides:

Divide both sides by 2:

Now we know the value of x, however, our work isn't done. They want to know the perimeter, so we need to substitute x in as 5.
Let's do it on the triangle.
(remember, this is our simplified version of the triangle)

Hope this helped!
To find the interior angle of any regular polygon you can use the formula

where n is the number of sides
So,

The measure of an interior angle in a regular octagon is 135
Answer:
45
Step-by-step explanation:
The answer is 63,800 mi²
hoped this helps