A circle is a figure in which each point around its perimeter is an equal distance from the center. The radius of a circle is the distance between the center and any point along its perimeter. A chord is a line segment that connects any two points along its perimeter. The diameter of a circle is the length of a chord that passes through the center of the circle and equals twice the circle's radius (2r).

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

sa = 2πr² + 2πrh
sa = 2π(6²) + 2π(6 x 2)
sa = 2π(36) + 2π(12)
sa = (2 x 36)π + (2 x 12)π
sa = 72π + 24π
sa = 96π

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

-3c - 6y = -9c + 5y - 1
-3c = -9c + 5y - 1 + 6y
-3c + 9c = 5y - 1 + 6y
6c = 11y - 1
c = \( \frac{11y - 1}{6} \)
c = \( \frac{11y}{6} \) + \( \frac{-1}{6} \)
c = 1\(\frac{5}{6}\)y - \(\frac{1}{6}\)

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°).

Perimeter is equal to the sum of the four sides:

p = a + b + c + d
p = 3 + 7 + 5 + 6
p = 21