As promised, here is a quick demo of how to find a zero of a function using your TI graphing calculator: (ie solving the equation 2sin x + 1 = 0)

 

And here is one that demos finding the intersection between a function and a horizontal line: (ie solving the equation 2sin x + 1 = 2.1)

 

And in honour of π day, of course, I give you Lady Vihart: