anonymous 5 years ago I need help on the intergral of cos (pi/20) :S

1. anonymous

in your integration there is no variable please write the question properly.

2. anonymous

the full question is, pi/10 x cos (pi/20)

3. anonymous

i think $\int\limits_{}^{}\cos \pi x/20dx$ let $y=\pi x/20$ after this substitution you will get dx=20 dy/pi$20/\pi \int\limits_{}^{}\cos y dy=-20\sin y/\pi =-(20/\pi)\sin (pix/20)$

4. anonymous

sin(pi/20)

5. anonymous

see if there is no x under cosine function then it is simply a constant and you can take it outside the integration

6. anonymous

Thankyou so Much :D

7. anonymous

8. anonymous

Just doing it now (:

9. anonymous

ok.

10. anonymous

11. anonymous

Maths is hard.

12. anonymous

are you talking in general or you haven't understand any step of mine?

13. anonymous