In triangle ABC, AB = AC = 25 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?
Since triangleEFC is iscoceles, AF+FC=AF+FE=25. This is also true for DE with triangleBDE also being iscoceles and AD+DB=AD+DE=25.
The perimeter of the paralellogram is (AD+DE)+(AF+FE) and we know that AD+DE=25 and AF+FE=25, so the answer is 25+25=50.
Hope this helped.