The area of a 7-by-3 rectangle is 7 × 3 = 21.
Rhombus: A rhombus is a four-sided figure with four equal sides.
All four sides of the quadrilateral above have the same length, so it’s a
rhombus. A rhombus is also a parallelogram, so to find the area of a rhombus,
you need its height. The more a rhombus “leans over,” the smaller the height
and therefore the smaller the area. The shape with the maximum area for a
rhombus of a certain perimeter is a rhombus that has each pair of adjacent
sides perpendicular, in which case you have a square.
Square: A square is a four-sided figure with four right angles and four equal
sides. A square is also a rectangle, a parallelogram, and a rhombus. The
perimeter of a square is equal to 4 times the length of one side.
Area of Square = (side)^2