Acute angle i think about 60
Rotate one of them so the right angle is in the same orientation as the other one.
1. AB = DE
2. CB = FE
3. AC = DF
4. Compare the length of two known sides: cb and EF
CB = 3 and EF = 8
8/3 = 2 2/3 scale factor
5. Ab is side de. Multiply the length of ab by the scale factor:
4 x 2 2/3 = 10 2/3
6. FD = sqrt ( 10 2/3^2 + 8^2)
FD = 13 1/3
12/100 = 3/25
hope it helps
