Examples of the use of Geometry formulas:
Find the perimeter of a parking lot that has a length of 50 yards and a width of 40 yards.
P = 2L + 2W = 2(50) + 2(40)= 180 yards
Find the perimeter of a triangle with sides of 2 inches, 4 inches, and 5 inches.
P = S+S+S = 2+4+5 = 11 inches
Find the area of a rectangular flag that has a length of 7 feet and a width of 2 feet.
A = LW = 7(2) = 14 square feet
Find the circumference and the area of a circle whose radius is 4 cm. Use 3.14 as an approximation of π.
Find the volume of a rectangular box with a length of 5 inches, a width of 6 inches and a height of 7 inches.
V=LWH = 5(6)(7)=210 cubic inches
(The surface area of this prism is calculated in the next example.)
Surface Area of a Rectangular Prism formula is A = 2ab + 2bc + 2ac
The surface area of a rectangular prism is the area of the six rectangles that cover it. Think of this like trying to cover a gift box with wrapping paper. The top and bottom are the same, the front and back are the same, and the left and right sides are the same.
The left and right side each have
side lengths of a and b, so the surface area of one of them is a*b, two
of them would be 2ab. The area of the top or bottom (side lengths a and
c) would be a*c, both of them together would be 2ac.
So then the surface area would be
A = 2(30) + 2(42) = 2(35) = 214 square inches or in2
The views and
opinions expressed in this page are strictly those of Mary Lou Baker. This page was edited on
The views and
opinions expressed in this page are strictly those of Mary Lou Baker.
This page was edited on 28-Jan-2013