# Math Help - How do you implicitly differentiate a trig funciton

1. ## How do you implicitly differentiate a trig funciton

Hi everybody. I'm new here. I am now working on a calculus problem on implicit differentiation, but I am kinda lost. The question asks me to differentiate x cos y = 1. I have no clue how to start. Can anyone please help me? Thanks a lot.

2. I would just use the product rule:

$\cos y + x(-\sin y)\frac{dy}{dx} = 0$

Or you can use the Implicit Function Theorem.