Problem:
Points A,B,C and D have these coordinates: A(3,2),B(3,−2),C(−3,−2) and D(−3,0). The area of quadrilateral ABCD is
Answer Choices:
A. 12
B. 15
C. 18
D. 21
E. 24
Solution:
The lower part is a 6×2 rectangle with area 12 . The upper part is a triangle with base 6 and altitude 2 with area 6. The total area is 12+6=18.
OR
Trapezoid ABCD has bases 2 and 4 with altitude 6. Using the formula:
A=2h(b1​+b2​)​, the area is 26(2+4)​=18.
Answer: C​.
The problems on this page are the property of the MAA's American Mathematics Competitions
.jpg)
