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.

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

a = l x w
a = a x b
a = 1 x 3
a = 3

To multiply monomials, multiply the coefficients (the numbers that come before the variables) of each term, add the exponents of like variables, and multiply the different variables together.

(7a)(7ab) + (9a²)(4b)
(7 x 7)(a x a x b) + (9 x 4)(a² x b)
(49)(a¹⁺¹ x b) + (36)(a²b)
49a²b + 36a²b
85a²b

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

The volume of a cylinder is πr²h:

v = πr²h
v = π(8² x 3)
v = 192π