what is the formula to find the perimeter of a rectangle: the length is twice it's width and the area is 200 ft sq.
"The formula" is what you need to come up with!
Since length is defined in terms of width, pick a variable for the width. Then
translate the relationship of "the length is twice the width" into a mathematical expression.
Take the
geometrical formula for the area "A" of a rectangle with width "w" and length "L", and plug your variable, your expression, and the given value for A into this formula.
Solve for the width. Back-solve for the length. Then plug these values into the formula for the perimeter P of a rectangle with width w and length L.
If you get stuck, please reply showing how far you have gotten. Thank you!