Area

• The area of a circle = πr² (π = 3.1416, r stands for radius).
  The area of a square = a² (a is the length of a side).
  The area of a rectangle = length X width.
  The area of a triangle = ½ X base X perpendicular height.
  
  

Surface Area

• The surface area of a cube = 6a² (a is the length of a side).
  The surface area of a rectangular prism = 2hw + 2hl + 2lw (h is height, w is width, l is length).
  
  

Volume

• The volume of a cube = a³ (a is the length of a side).
  The volume of a rectangular solid = length X width X height.
  The volume of a cylinder = πr²h (r is radius of the circle atop the cylinder and h is the height).
  
  

Perimeter

• The perimeter of a square = 4x (x is the length of a side).
  The perimeter of a rectangle is 2 X (length of the long side of the rectangle + length of the short side).
  The perimeter of a triangle = a X b X c (a, b and c are the length of one of the triangle's side).
  The circumference of a circle = 2πr.
  
  

Algebraic

• (a + b)² = a² + 2ab + b².
  (a - b)² = a² - 2ab + b².
  (a + b + c)² = a² + b² + c² + 2(ab + bc + ca).