what's the indefinite integral

[afcwestwarrior]

of sin pi x dx

i thought it would be - cos pi x dx but i think it might be (1/pi) -cos pi x dx

[Anthony]

\int \sin (\pi x)\, \mathrm{d}x =\frac{1}{\pi} \int \sin (\pi x) \, \mathrm{d} (\pi x)

Does this help?

[afcwestwarrior]

yea a lot thanks, i guessed right but i didn't know if i was right

[afcwestwarrior]

just wondering why is it 1/pi, i'm not even sure why

[HallsofIvy]

What is the derivative of cos(pi x)?

[afcwestwarrior]

it's - sin (pi x)

[NoMoreExams]

To integrate sin( \pi x) dx consider doing a substitution of u = \pi x then substitute in the appropriate expression of dx in terms of du.

[HallsofIvy]

it's - sin (pi x)
Well, there is you problem then: it isn't. Use the chain rule.