SHAPES AND FIGURES OF PLANE GEOMETRY
The perimeter of a triangle is calculated using the formula:
P = side1 + side2 + side3.
The area of a traingle is always expressed in square units, and the perimeter of a triangle is
always expressed in the original units.
Calculate the area and perimeter of a right triangle with a 9" base and sides measuring
12" and 15". Be sure to include the units in your answer.
A = 1/2 bh
P = s1 + s2 + b
A = .5(9)(12)
P = 9 + 12 + 15
A = .5(108)
P = 36 inches
A = 54 square inches
Figure 10 Parallelogram
quadrilateral with both pairs of opposite
sides parallel, as shown in Figure 10.
The area of the parallelogram is calculated
using the following formula:
A = (base) (height) = bh
The perimeter of a parallelogram is calculated using the following formula:
P = 2a + 2b
The area of a parallelogram is always expressed in square units, and the perimeter of a
parallelogram is always expressed in the original units.