This is the first in a series of doodles out of my (actual) math homework.
My math homework is usually pretty eccentric, if that's even possible.
Anyway...

Occasionally, it is effective to know the transforms and identities of trigonometry when attempting to solve higher level calculus problems.

For these moments, I have made friends with the Trig Witch, whose unit circles and special triangles have gotten me through at least one line integral unscathed.