Problem:
In â–³ABC,AB=AC=28 and BC=20. Points D,E, and F are on sides AB, BC, and AC, respectively, such that DE and EF are parallel to AC and AB, respectively. What is the perimeter of parallelogram ADEF ?
Answer Choices:
A. 48
B. 52
C. 56
D. 60
E. 72
Solution:
Because EF is parallel to AB, it follows that △FEC is similar to △ABC and FE=FC. Thus half of the perimeter of ADEF is AF+FE= AF+FC=AC=28. The entire perimeter is 56​ .
The problems on this page are the property of the MAA's American Mathematics Competitions
