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

a = l x w
a = a x b
a = 5 x 8
a = 40

The volume of a cube is height x length x width:

v = h x l x w
v = 9 x 8 x 2
v = 144

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 -9 as well and sum (Inside, Outside) to equal 8. For this problem, those two numbers are -1 and 9. Then, plug these into a set of binomials using the square root of the First variable (y²):

y² + 8y - 9
y² + (-1 + 9)y + (-1 x 9)
(y - 1)(y + 9)

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).

According to the Pythagorean theorem, the hypotenuse squared is equal to the sum of the two perpendicular sides squared:

c² = a² + b²
c² = 9² + 1²
c² = 81 + 1
c² = 82
c = \( \sqrt{82} \)