# Finding the derivative

• Jan 17th 2008, 03:43 PM
Linnus
Finding the derivative
$Cos x= e^y$
0<x<pi/2
What is dy/dx in terms of x?
Thanks!
• Jan 17th 2008, 04:06 PM
Jhevon
Quote:

Originally Posted by Linnus
$Cos x= e^y$
0<x<pi/2
What is dy/dx in terms of x?
Thanks!

you may be thinking about differentiating implicitly, but it is possible to solve for y here

$\cos x = e^y \implies y = \ln ( \cos x)$

now, can you differentiate that? Hint: use the chain rule
• Jan 17th 2008, 04:17 PM
Linnus
ah, thanks, i can't believe I overlooked that