I have to find the area of this parallelogram, but the only three things I'm told are that AD = 5, EF = 11, and EFC = 90º. So far I've tried using the pythagoras theorem, and the special 30-60-90 triangle theorem (longer cathet = √3 * shorter cather OR (√3/2) * Hypotenuse), but they all lead to a dead end.