Finding partial derivative of a trig function

[lagwagon555]

Homework Statement

Find the partial derivative with respect to x of sin(xyz - 1)

Homework Equations

None needed.

The Attempt at a Solution

I took the answer to be yz*cos(xyz - 1), but wolfram alpha is giving me yz*cos(1 - xyz). Anyone know what's going on here? Thanks!

 

[thaer_dude]

cos(x) is equal to cos(-x)

Those answers are equivalent.

Btw, if you're confused as to what Wolfram Alpha is doing, press the "Show steps" button. Helps out sometimes.

 

[lagwagon555]

Ah right I see, thanks a lot for clarifying that. I'm taking a senior level maths paper after 2 years of not doing maths, so I keep slipping up on things like that. Thanks again :)