A circle is a figure in which each point around its perimeter is an equal distance from the center. The radius of a circle is the distance between the center and any point along its perimeter. A chord is a line segment that connects any two points along its perimeter. The diameter of a circle is the length of a chord that passes through the center of the circle and equals twice the circle's radius (2r).

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

a = l x w
a = a x b
a = 7 x 8
a = 56

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 20 as well and sum (Inside, Outside) to equal 9. For this problem, those two numbers are 4 and 5. Then, plug these into a set of binomials using the square root of the First variable (y²):

y² + 9y + 20
y² + (4 + 5)y + (4 x 5)
(y + 4)(y + 5)

To solve this equation, repeatedly do the same thing to both sides of the equation until the variable is isolated on one side of the > sign and the answer on the other.

-2x - 9 > 5 + 7x
-2x > 5 + 7x + 9
-2x - 7x > 5 + 9
-9x > 14
x > \( \frac{14}{-9} \)
x > -1\(\frac{5}{9}\)

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.