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.

An acute angle measures less than 90°, a right angle measures 90°, and an obtuse angle measures more than 90°.

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(8 + 6)(3)
a = ½(14)(3)
a = ½(42) = \( \frac{42}{2} \)
a = 21

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°).

You need to find the value of c so solve the first equation in terms of z:

6c + z = 6
z = 6 - 6c

then substitute the result (6 - 6c) into the second equation:

5c - 5(6 - 6c) = 6
5c + (-5 x 6) + (-5 x -6c) = 6
5c - 30 + 30c = 6
5c + 30c = 6 + 30
35c = 36
c = \( \frac{36}{35} \)
c = 1\(\frac{1}{35}\)