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 (First, Outside, Inside, Last) method in reverse.

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

The slope of this line is the change in y divided by the change in x. The endpoints of this line segment are at (-2, 1) and (2, -9) so the slope becomes:

To solve this equation, isolate the variable for which you are solving (b) on one side of the equation and put everything else on the other side.

-4b + 2x = 8b + x - 1
-4b = 8b + x - 1 - 2x
-4b - 8b = x - 1 - 2x
-12b = -x - 1
b = \( \frac{-x - 1}{-12} \)
b = \( \frac{-x}{-12} \) + \( \frac{-1}{-12} \)
b = \(\frac{1}{12}\)x + \(\frac{1}{12}\)