Can u help me with 3c please I really need help.

Express the following as a function of a single angle, cos(60) cos(-20) - sin(60) sin(-20)

Two lines parallel to a third line are parallel to each other. always sometimes or never

Aman is 6 feet 3 inches tall. the top of his shadow touches a fire hydrant that is 13 feet 6 inches away. what is the angle of elevation from the base of the fire hydrant to the top of the man's head?