DE and EF is a right triangle. Me personally...

• Set F as 1000/1000.

• Solve F to A, A to B, B to C. Now we have a coordinate on F and C

• Take advantage of the fact that DE and EF create a right triangle. This allows you to simply occupy F again and use the Azimuth of E to D (reverse DE) to calculate a coordinate. Inverse this to coordinate to C. You will get a triangle that you can solve CD. The reason you can do this is because you will have three azimuths on that triangle and a distance (the inverse you calculated) You should be able to do the law of sine to get CD.

• The nature of the above triangle will allow you to calculate EF as well.