★ Rectangular perimeter = (length+width) × 2 Rectangular area = surface area of long× wide cuboid = (length× width+length× height+width× height )× 2 cuboid volume = length× width× height or bottom area× height ★ Square perimeter = side length× 4 square area = side length× surface area of side-length cube = side length× side length. ★ Triangle area = base × height ÷2 ★ parallelogram area = base × height ★ trapezoid area = (upper base+lower base) × height ÷2 ★ circumference of a circle = ∈× diameter, that is, c = ∏ d × radius ×2, that is, c = 2 ∏. The circumference of = half a circle+diameter, namely: ∏ r+2 r ★ Surface area of cylinder =2 bottom areas+lateral area lateral area = Perimeter of bottom surface × Height ★ Volume of cylinder = Bottom area× Volume of high cone = Bottom area× Height ÷ 3.