# differentiate trig function

• Oct 5th 2008, 11:51 AM
thecount
differentiate trig function
Differentiate

y= 2 csc x + 5 cos x

I don't think I am doing this right..
• Oct 5th 2008, 12:03 PM
Chop Suey
$\frac{d}{dx}cf(x) = cf'(x)$

$\frac{d}{dx}\csc{x} = -\csc{x}\cot{x}$

$\frac{d}{dx}\cos{x} =-\sin{x}$

Post your answer here to see if it's correct or not.
• Oct 5th 2008, 12:05 PM
o_O
The derivative of a sum is the sum of its derivatives: $\frac{d}{dx} \left[ f(x) + g(x) \right] = \frac{d}{dx} f(x) + \frac{d}{dx} g(x)$

So just differentiate each term. What's the derivative of $\csc x$? How about that of $\cos x$?
• Oct 5th 2008, 12:08 PM
thecount

-2 csc x cot x - 5 sin x
• Oct 5th 2008, 12:15 PM
Chop Suey
Correct. (Clapping)