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 first step to solve a quadratic expression that's not set to zero is to solve the equation so that it is set to zero:

x² + 6x - 33 = 2x - 1
x² + 6x - 33 + 1 = 2x
x² + 6x - 2x - 32 = 0
x² + 4x - 32 = 0

Next, factor the quadratic equation:

x² + 4x - 32 = 0
(x - 4)(x + 8) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (x - 4) or (x + 8) must equal zero:

If (x - 4) = 0, x must equal 4
If (x + 8) = 0, x must equal -8

So the solution is that x = 4 or -8

To factor a quadratic expression, apply the FOIL method (First, Outside, Inside, Last) in reverse. First, find the two Last terms that will multiply to produce 18 as well and sum (Inside, Outside) to equal 11. For this problem, those two numbers are 2 and 9. Then, plug these into a set of binomials using the square root of the First variable (y²):

y² + 11y + 18
y² + (2 + 9)y + (2 x 9)
(y + 2)(y + 9)

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

a = l x w
a = a x b
a = 5 x 3
a = 15

A right angle measures 90 degrees and is the intersection of two perpendicular lines. In diagrams, a right angle is indicated by a small box completing a square with the perpendicular lines.