A line on the coordinate grid can be defined by a slope-intercept equation: y = mx + b. For a given value of x, the value of y can be determined given the slope (m) and y-intercept (b) of the line. The slope of a line is change in y over change in x, \({\Delta y \over \Delta x}\), and the y-intercept is the y-coordinate where the line crosses the vertical y-axis.

A triangle is a three-sided polygon. It has three interior angles that add up to 180° (a + b + c = 180°). An exterior angle of a triangle is equal to the sum of the two interior angles that are opposite (d = b + c). The perimeter of a triangle is equal to the sum of the lengths of its three sides, the height of a triangle is equal to the length from the base to the opposite vertex (angle) and the area equals one-half triangle base x height: a = ½ base x height.

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

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

sa = 2πr² + 2πrh
sa = 2π(2²) + 2π(2 x 9)
sa = 2π(4) + 2π(18)
sa = (2 x 4)π + (2 x 18)π
sa = 8π + 36π
sa = 44π

The area of a triangle is equal to ½ base x height:

a = ½bh
a = ½ x 6 x 9 = \( \frac{54}{2} \) = 27