Logan county is square. it had a side that is 15.4 miles long. what is the area?

First of all, we know that Logan's County has the shaped of square, and the question states that to find the area of his county. To find the area, we will use Area of square formula.
A=s•s where s represent the side of his county which is 15.4 miles long, so we just beed to do now is substitute s with 15.4
A=s•s
A=15.4•15.4
A=237.16 square miles. As a result, the area of Logan's County is 237.16 square miles. Hope it help!

The area of any rectangle is xy where xy are the dimensions of the rectangle.  A square is just a special rectangle where x=y so it's area is:

A=x^2 where x is its side length, in this case 15.4 miles

A=15.4^2

A=237.16 mi^2