## Skip2mylou426 one year ago Find the integral of (cos^2(x))((cosxsin^2n+1)*(pi/2*sinx)+(sinxsin^2n+1)(pi/2*cosx)) from 0 to pi/2

1. primeralph

Input it more clearly.

2. Skip2mylou426

$\int\limits_{0}^{\pi/2}\cos ^{2}x(\cos x \sin ^{2n+1}(\frac{ \pi }{ 2 }sinx)+sinxsin ^{2n+1}(\frac{ \pi }{ 2 }cosx))dx$

3. primeralph

Go Wolfram.

4. Skip2mylou426

I don't have the first clue on how to use that

5. primeralph
6. swissgirl

Wolfram sucks these days :(

7. primeralph

How?

8. swissgirl

Thats what happens with all these free awesome programs

9. primeralph

Well, I don't think it even has CAS. I don't use it though.

10. swissgirl

Well if you wanna see the steps then you gotta have membership

11. primeralph

Well, I'd expect them to do that.

12. swissgirl

Ummm this is an annoying function. @Skip2mylou426 what r u currently studying?

13. swissgirl

Wolfram was the best matrix calculator .........

14. primeralph

was?

15. primeralph

Think it's always been Matlab......

16. swissgirl

Welll ya Dont have matlab. I used to have mathematica but my comp broke down so dont have it no more :(

17. primeralph

@Skip2mylou426 I think the integral can't be evaluated easily because of the form sin(acos(b))

18. primeralph

@swissgirl Yeah, if you're into coding, you'll fancy Matlab.

19. swissgirl

I guess he went to the lou :)

20. Skip2mylou426

I was trying to type that monstrosity into Wolfram. Epic fail. It didn't work at all.

21. doulikepiecauseidont
22. swissgirl

OMG IK THAT

23. swissgirl

It always happens to me

24. primeralph

There is no free CAS engine...........unless you can hack. Otherwise, get your pen and paper.

25. swissgirl

wait let me try wolframming it for u

26. Skip2mylou426

A little rusty on the calculus. I haven't taken calc in 3 or 4 years unfortunately

27. swissgirl

What course are u taking now?

28. primeralph

@swissgirl No point. The integrand has the form of a switch variable 'n' which would leave the answer not numeric, but algebraic........which requires a CAS software.

29. Skip2mylou426

It's called Problem Solving. It's a combination of every type of math course that could've possibly been taken.

30. swissgirl

FUNNNNNN :)

31. Skip2mylou426

haha not quite. He only gives us 1 point per problem solved. All work is required and 500 points are needed to get an A. Class has one month left (halfway done) and I have 178 points right now. KILL ME.

32. primeralph

I don't see the point in putting that into an integral. The integrand can be simplified though....it just looks ugly.

33. primeralph

|dw:1372916840241:dw|

34. primeralph

|dw:1372917002693:dw|

35. primeralph

.........then you start using the identities......

36. swissgirl

Ohhhh cooollll Ya I shld have thought of cleaning it up by using identities :)

37. primeralph

Yeah, I'm sure you'd have figured it out eventually. It's just boring to look at.

38. Skip2mylou426

so clean it up using identities, then plug in?

39. Skip2mylou426

is that a square that cuts off at the end?

40. swissgirl

Yes it is

41. primeralph

|dw:1372917328459:dw|

42. Skip2mylou426

thanks! think it'll be messy if I don't use identities first?

43. primeralph

Well, depending on how much math you know, yes and no. You might be able to notice the symmetry; and if you can't fiddle with it,

44. hobbs978

45. hobbs978

just thought i would point that out

46. primeralph

@hobbs978 Thanks. Yours too. No homo.

47. Skip2mylou426

48. primeralph

You're welcome. Sorry I couldn't finish it; I'm kinda tired today.

49. Skip2mylou426

It's ok, I wish I even remembered how to start it. I feel like a failure.

50. swissgirl

hahaha dont feel like one I took 2 semesters of stats earlier this yr and I cant remember pellet Yesterday I was looking at a question and was totally blank. I felt like the biggest failure

51. primeralph

It's funny how the system changes your words by itself. We know what you meant to type instead of "pellet"........

52. primeralph

@Skip2mylou426 http://www.sosmath.com/trig/Trig5/trig5/trig5.html

53. Skip2mylou426

So after plugging everything in...I come up with a big fat zero...

54. swissgirl

hahahahaha :D Just smile

55. primeralph

Well, zero is an answer...in many cases.

56. Skip2mylou426

I may have made a mistake. ugh. ok I'm going to attempt to draw this.. hold on

57. Skip2mylou426

|dw:1372918536405:dw|

58. Skip2mylou426

ok so the $\cos(0)^3$ is going to be equal to one and then I end up with..

59. primeralph

0

60. Skip2mylou426

|dw:1372918796639:dw|

61. Skip2mylou426

62. primeralph

Still 0

63. Skip2mylou426

Ok that's what I originally had. Sorry, don't hate me

64. primeralph

No, I don't hate you. Stop bringing yourself down. Sure you're an awesome student.

65. Skip2mylou426

I'm trying, I really am, but this class is insanely hard. The hardest class in our program is Modern Algebra (which I took last semester), and I thought that was easier than this. I'm at a loss. I don't know what to do.

66. swissgirl

Modern Algebra = Abstract Algebra?

67. Skip2mylou426

Give or take. Our professor wrote the text for it

68. primeralph

69. swissgirl

Ok that is a really hard course.

70. swissgirl

71. primeralph

Well, it means you can't find the answers elsewhere......since the professor made them up.

72. swissgirl

hahahaha yaaaaaa My abstract algebra course was customized too

73. Skip2mylou426

Almost our whole department is like that. The worst thing is that the majority of our professors are research-based and suck at teaching.

74. swissgirl

Like most profs out there who cant teach

75. primeralph

I learned a long time ago to never expect a professor to teach well. I just get the syllabus and do my thing.

76. Jhannybean

Exactly...

77. Jhannybean

Hmm.. @satellite73 perhaps?...

78. Skip2mylou426

that's the issue with this class, he just gives you a bunch of problems with no material to work with

79. primeralph

Get "Engineering Math by KA Stroud" Then go to "Advanced Engineering Math" by anybody.......but Kreyszig........that'll be later because it doesn't explain easy.

80. primeralph

81. Skip2mylou426

I probably lack the necessary skills to do that. Can't hurt to try though

82. swissgirl

Ya I only do free stuff. I got mathematica for free and all my textbooks in pdf formats

83. Jhannybean

84. primeralph

@Skip2mylou426 The first book explains quite well. I've used it for HS students, so it should be cool.

85. Skip2mylou426

I'll have to check it out soon. Thanks again for your help, I think I'm going to go die now :)

86. primeralph

Stay safe.

87. experimentX

$\frac{2 (1)_{n-1}}{\pi \left( \frac 3 2\right)_{n-1} }$ http://mathworld.wolfram.com/PochhammerSymbol.html