In a rectangular coordinate system, what is the area of a quadrilateral whose vertices have the coordinates (3,-1), (3, 8), (12, 2), (12,-7)?
Choose the correct choice from the following choices.
A) 69
B) 75
C) 81
D) 87
E) 93
By graphing the points, we can see that this figure is a trapezoid. A trapezoid is any quadrilateral that has one set of parallel sides, and the formula for the area of a trapezoid is:   Area = (1/2) × (Base 1 + Base 2) × (Height), where the bases are the parallel sides.   We can now determine the area of the quadrilateral:   Area = 1/2 × (9 + 9) × 9 = 81.   The answer is 81.
<result>C</result>
In a rectangular coordinate system, what is the area of a quadrilateral whose vertices have the coordinates (3,-1), (3, 8), (12, 2), (12,-7)?