Section 2.3: Area
Section 2.3 – Area
The area of a two-dimensional figure describes the amount of surface the shape covers. You measure area in square units of a fixed size. Examples of square units of measure are square inches, square centimeters, or square miles. When finding the area of a polygon, you count how many squares of a certain size will cover the region inside the polygon.
The formulas you are going to look at are all developed from the understanding that you are counting the number of square units inside the polygon.
| Shape | Area |
Rectangle with side lengths a, b |
𝐴 = a ∙ b |
|
Parallelogram with height h and base b
|
𝐴 = 𝑏 ∙ ℎ |
|
Triangle with height h and base b
|
𝐴 = [latex]\frac{1}{2}[/latex]𝑏ℎ |
| Trapezoid as shown below:
|
𝐴 = [latex]\frac{b_1~+~b_2}{2}[/latex]ℎ |
