To draw the shear diagram:
- At segment AB, the shear is uniformly distributed at 1900 lb.
- A shear of -100 lb is uniformly distributed over segments BC and CD.
To draw the Moment Diagram:
- MAB = 1900x is linear; at x = 0, MAB = 0; at x = 3 ft, MAB = 5700 lb·ft.
- For segment BC, MBC = -100x + 6000 is linear; at x = 3 ft, MBC = 5700 lb·ft; at x = 9 ft, MBC = 5100 lb·ft.
- MCD = -100x + 1200 is again linear; at x = 9 ft, MCD = 300 lb·ft; at x = 12 ft, MCD = 0.