Question

Polygon ABCD has the following vertices:

A(−4, 2), B(3, 2), C(3, −5), and D(−4, −2)

Calculate the area of the polygon.

Answer 1

The answer is 38.5. I took this exam and I chose 38.5 and got it right, I hope this helps!

Answer 2

To be able to solve clearly this problem, the best thing to do is to plot the graph (see attached pic). From the graph we can see that the points form a trapezoid.

The base is formed by the segment connecting point A and point B.

While the two heights: shorter one by the segment connecting points A and D, and the longer one by the segment connecting points B and C.

The formula for area of trapezoid is given as:

A = b (h1 + h2) / 2

Where,

b = base of the trapezoid = 3 – (-4) = 7

h1 = shorter height = 2 – (-2) = 4

h2 = longer height = 2 – (-5) = 7

Therefore the area is:

A = 7 (4 + 7) / 2

A = 77 / 2

A = 38.5