Parallel lines are lines that share the same slope (steepness) and therefore never intersect. A transversal occurs when a set of parallel lines are crossed by another line. All of the angles formed by a transversal are called interior angles and angles in the same position on different parallel lines equal each other (a° = w°, b° = x°, c° = z°, d° = y°) and are called corresponding angles. Alternate interior angles are equal (a° = z°, b° = y°, c° = w°, d° = x°) and all acute angles (a° = c° = w° = z°) and all obtuse angles (b° = d° = x° = y°) equal each other. Same-side interior angles are supplementary and add up to 180° (e.g. a° + d° = 180°, d° + c° = 180°).

The surface area of a cylinder is 2πr² + 2πrh:

sa = 2πr² + 2πrh
sa = 2π(1²) + 2π(1 x 9)
sa = 2π(1) + 2π(9)
sa = (2 x 1)π + (2 x 9)π
sa = 2π + 18π
sa = 20π

The area of a triangle is equal to ½ base x height:

a = ½bh
a = ½ x 1 x 5 = \( \frac{5}{2} \) = 2\(\frac{1}{2}\)

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

a = l x w
a = a x b
a = 7 x 9
a = 63

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 - 3)(y - 8)
(y x y) + (y x -8) + (-3 x y) + (-3 x -8)
y² - 8y - 3y + 24
y² - 11y + 24