# Math Help - How to differentiate these using first principles?

1. ## How to differentiate these using first principles?

I know how to differentiate Sin x and Cos x using first principles.But how to do that to cosec x and sec x?
Thanks

2. $\sec(x+h) = \dfrac{1}{\cos(x+h)}$

So you'd have

$f'(x) = \lim_{h \to 0} \dfrac{\dfrac{1}{\cos(x+h)} - \dfrac{1}{\cos(x)}}{h}$