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°).

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 45 as well and sum (Inside, Outside) to equal -14. For this problem, those two numbers are -9 and -5. Then, plug these into a set of binomials using the square root of the First variable (y²):

y² - 14y + 45
y² + (-9 - 5)y + (-9 x -5)
(y - 9)(y - 5)

A trapezoid is a quadrilateral with one set of parallel sides.

The area of a trapezoid is one-half the sum of the lengths of the parallel sides multiplied by the height:

a = ½(b + d)(h)
a = ½(6 + 9)(4)
a = ½(15)(4)
a = ½(60) = \( \frac{60}{2} \)
a = 30

A quadrilateral is a shape with four sides. The perimeter of a quadrilateral is the sum of the lengths of its four sides.