**Chapter 12 Formulas**

**Base Area Formulas "B"**

Rectangle or square = base * height

Square = 1/2 * diagonal #1 *diagonal #2

Triangle = base * height / 2

Trapezoid = 1/2 * height * (base1 + base2)

Circle = pi * radius^2

Pentagon, Hexagon, Octagon, Decagon Equilateral Triangle= Perimeter * apothem / 2

(Follow the a, b, s, P, A sequence to find the area of these regular
polygons!!)

__Perimeter and Circumference Formulas__

Polygon = (add ** all** sides)

Circle = 2 * r * pi

__Prisms and Cylinders__

Surface Area = (2*Base Area) + (Perimeter * height)

Volume = Base Area * height

__Pyramids and Cones__

Surface Area = Base Area + 1/2 * Perimeter *slant height

Volume = Base Area * height / 3

__Spheres__

Surface Area = 4 * pi * radius^2

Volume = 4/3 * pi * radius^3