SHAPES AND FIGURES OF PLANE GEOMETRY
Geometry
The perimeter of a triangle is calculated using the formula:
P = side1 + side2 + side3.
(3-2)
The area of a traingle is always expressed in square units, and the perimeter of a triangle is
always expressed in the original units.
Example:
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.
Solution:
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
Quadrilaterals
Figure 10 Parallelogram
A
quadrilateral
is
any
four-sided
geometric figure.
A
parallelogram
is
a
four-sided
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
(3-3)
The perimeter of a parallelogram is calculated using the following formula:
P = 2a + 2b
(3-4)
The area of a parallelogram is always expressed in square units, and the perimeter of a
parallelogram is always expressed in the original units.
MA-03
Page 8
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