I hope someone can help. I'm currently stuck on a question which requires me to verify that a given function's tangent is zero, by using the difference quotient. As a reminder, the difference quotient follows this form: f(x+h) + f(x)/h.

The thing is that I know how to use the difference quotient for quadratic functions, but not for trig functions.

**I'm really looking for guidance on how to do this (i.e. how trig functions look like in difference quotient form).**I attached the questions that I need guidance on in this post (5c and 5b). If someone could show the first few steps of 5c and 5b, that would be wonderful.

Cheers,

- Olivia