1, rectangle perimeter = (length+width) ×2 rectangle length = perimeter ÷2— wide rectangle width = perimeter ÷2— long rectangle area = length × width = area ÷ width = area perimeter ÷ long square = side length ×4.

Side length = perimeter ÷4 square area = side length × side length

2. The perimeter of a triangle = the sum of three sides; Area of triangle = base × height ÷ 2; Height of triangle = area ÷ base ×2. The base of triangle = area/height ×2.