situational problems involving "circular functions" with solution

Answer 1

circular "functions are not functions, they are circular relations

but some periodic relations are functions

standard trig functions are not one-to-one functions, as they fail the horizontal line test,

y=cotx is a function, but not one-to-one

some situations invove light beams moving on a wall, its changing speed and the angle formed with the horizontal as the light rotates. the angle = cot^-1(y)=x