Answer:
[tex]Area = 2900[/tex]
Step-by-step explanation:
Given
[tex]A (x_1,y_1) = (40,20)[/tex]
[tex]B (x_2,y_2) = (80,20)[/tex]
[tex]C (x_3,y_3) = (100,70)[/tex]
[tex]D (x_4,y_4) = (40,70)[/tex]
Required
Determine the Area
The area of the section is:
[tex]Area = \frac{1}{2}|(x_1y_2 + x_2y_3 + x_3y_4 + x_4y_1) - (y_1x_2 + y_2x_3 + y_3x_4 + y_4x_1)|[/tex]
Substitute values for the x's and y's
[tex]Area = \frac{1}{2}|(40 * 20 + 80*70 + 100*70 + 40*40) - (20*80 + 20*100 + 70*40 + 70*40)|[/tex]
[tex]Area = \frac{1}{2}|15000 - 9200|[/tex]
[tex]Area = \frac{1}{2}|5800|[/tex]
[tex]Area = \frac{1}{2} * 5800[/tex]
[tex]Area = 2900[/tex]
Hence, the area of the section is 2900ft^2
