For the figure shown:

a$)$ Find the Cartesian components of the reactions at supports A and $D.$

b$)$ Prepare the complete shear diagram of the ABC beam section and indicate the point or section at which the maximum shear occurs.

c$)$ Prepare the bending moment diagram of the ABC beam section and indicate the point or section in which the maximum bending moment occurs. Also indicate the intersection points with the $x$ axis if there are any.

d$)$ Indicate the degree of the polynomials that define the shear force and bending moment curves.