Angle A is 30 degrees and angle D is arccos(3/5)
The area of triangle ABC is 5*sqrt(3), and the area of triangle DEF is 9.
Height BX = sinA * 4 = 2
[ABC] = 1/2(2 * 5) = 5
Height EY = sinD * 4 = 3.2
[DEF] = 1/2(3.2 * 5) = 8