Introduction to Area of Geometric Figures
Circles to square and cubes to double would give a man excessive trouble. —Matthew Prior(1664–1721)
This lesson will explore area and how to identify it for common and irregular shaped figures.
Area is a measure of how many square units it takes to cover a closed figure. Area is measured in square units.
Area is a multiplication concept, where two measures are multiplied together. You can also think of units being multiplied together: cm × cm = cm^{2}, or the words centimeters squared.
When you measured lengths, you used different units, like feet, meters, inches, and so on. When you find the area, you use square units.
Here are the area formulas that you should know.
When calculating the area of a circle, you will see the π symbol. π, also called pi, is known as a mathematical constant, and represents the number 3.14159. (We often use 3.14.)
Let's try finding the area of the parallelogram.
Because the figure is a parallelogram, the height is the length that is perpendicular to the base, not a side of the figure. The base is 300 cm, and the height is 1.5 m. Before using the area formula, all units need to be consistent. Change 300 cm into meters before proceeding. There are 100 centimeters in a meter; therefore, there are 300 divided by 100 meters, which is 3 meters in the base.
Use the area formula and substitute in the given lengths: | A = bh |
Multiply the base times the height: | A = 1.5 × 3 |
A = 4.5 | |
Include the square units: | A = 4.5 m^{2} |
Find practice problems for these concepts at Area of Geometric Figures Practice Questions.
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