Angles around a line add up to 180°. Angles around a point add up to 360°. When two lines intersect, adjacent angles are supplementary (they add up to 180°) and angles across from either other are vertical (they're equal).

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°).

A rhombus is a parallelogram with four equal-length sides. A square is a rectangle with four equal-length sides.

The first step to solve a quadratic expression that's not set to zero is to solve the equation so that it is set to zero:

z² - 11z + 27 = z - 5
z² - 11z + 27 + 5 = z
z² - 11z - z + 32 = 0
z² - 12z + 32 = 0

Next, factor the quadratic equation:

z² - 12z + 32 = 0
(z - 4)(z - 8) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (z - 4) or (z - 8) must equal zero:

If (z - 4) = 0, z must equal 4
If (z - 8) = 0, z must equal 8

So the solution is that z = 4 or 8

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.