Using Stewart's theorem, you can find that BM and CM are both √37 and not 4√2, which means our third side (BC) is of length 2√37 (= √148)
Then, using Heron's formula given by:
16|△ABC|2=2a2b2+2b2c2+2c2a2−a4−b4−c4
you can calculate the area to be equal to exactly 42