# Math Help - TI-89 Integrating Incorrectly

1. ## TI-89 Integrating Incorrectly

This is what my calculator is giving me:

$
\int {\cos (1 - x)dx = \sin (x - 1)}
$

This is obviously wrong. Could anyone explain why it's doing this?

2. Hello,
Originally Posted by RedBarchetta
This is what my calculator is giving me:

$
\int {\cos (1 - x)dx = \sin (x - 1)}
$

This is obviously wrong. Could anyone explain why it's doing this?
I'm finding it correct

It's just that -sin(x)=sin(-x) and hence the result

3. It is not wrong.

$\int \cos{(1-x)} dx = -\sin{(1-x)} = \sin{(-(1-x))} = \sin{(x-1)}$

Recall that Sine is an odd function:
$\sin{(-u)} = -\sin{u}$

4. I didn't notice the change from (1-x) to (x-1)