A rectangle is a parallelogram containing four right angles. Opposite sides (a = c, b = d) are equal and the perimeter is the sum of the lengths of all sides (a + b + c + d) or, comonly, 2 x length x width. The area of a rectangle is length x width. A square is a rectangle with four equal length sides. The perimeter of a square is 4 x length of one side (4s) and the area is the length of one side squared (s²).

The area of a rectangle is equal to its length x width:

a = l x w
a = a x b
a = 3 x 4
a = 12

To multiply binomials, use the FOIL method. FOIL stands for First, Outside, Inside, Last and refers to the position of each term in the parentheses:

(y + 2)(y - 1)
(y x y) + (y x -1) + (2 x y) + (2 x -1)
y² - y + 2y - 2
y² + y - 2

To combine like terms, add or subtract the coefficients (the numbers that come before the variables) of terms that have the same variable raised to the same exponent.

2a - 8a = -6a

The volume of a cylinder is πr²h:

v = πr²h
v = π(2² x 3)
v = 12π