ab^2 = be^2 + ae^2 pythagorean theorem e is the point below b
6.5^2 = 6^2 + ae^2
42.25 = 36 +ae^2
6.25 = ae^2
2.5 = ae
23 = ae +ef +fd f is the point below c
23 = 2.5 + 9 +fd
fd = 11.5
tan D = opp/adj
tan D= cf /fd
tan D = 6/11.5
D = tan^-1 (6/11.5)
D =27.5528
D = 27.6 degrees