I have a couple of problems to check over for correction. I'm either over-complicating or over-simplifying them, ahahaha...

Please consider these... They're probably really easy...

Thank you!

(*) A rectangle has an area of 38 square feet. Determine the perimeter as a function of the lengthl.

(*) The volume of a right circular cylinder is 540 cubic centimeters. Express the height of the cylinder as a function of its radiusr.

(*) The hypotenuse of a right triangle is twice as long as the height. Determine the height as a function of the baseb.