Hi, I can't integrate sin x cos x. I tried a u substitution with u=sinx and dx=cos x du and got 1/2(sin x)^2+c. My text book answer is -1/4cos 2x+c.

Can someone please show where I am going wrong?

Is my u substitution wrong?

Thank you

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- Jul 5th 2009, 03:38 PMslaypullingcattrig integration
Hi, I can't integrate sin x cos x. I tried a u substitution with u=sinx and dx=cos x du and got 1/2(sin x)^2+c. My text book answer is -1/4cos 2x+c.

Can someone please show where I am going wrong?

Is my u substitution wrong?

Thank you - Jul 5th 2009, 03:52 PMskeeter
- Jul 5th 2009, 03:53 PMVonNemo19
- Jul 5th 2009, 04:00 PMslaypullingcat
- Jul 5th 2009, 04:15 PMskeeter
$\displaystyle \int \sin{x} \cos{x} \, dx$

$\displaystyle \frac{1}{2} \int 2\sin{x} \cos{x} \, dx$

$\displaystyle \frac{1}{2} \int \sin(2x) \, dx$

can you get the textbook solution from this? - Jul 5th 2009, 05:49 PMslaypullingcat