## saifoo.khan 2 years ago Differentiate: sin(x)*cos(2x)

1. RolyPoly

$\frac{d}{dx}sinxcos(2x) = \frac{d}{dx}sinx(1-2sin^2x)$Does that help?

2. saifoo.khan

Umm. Sorry no. I have to use the chain rule. @RolyPoly

3. saifoo.khan

@yummydum : That won't work. :P

4. yummydum

i realized that :P

5. RolyPoly

$\frac{d}{dx}sinxcos(2x) = cos(2x)\frac{d}{dx}sinx+sinx \frac{d}{dx}cos(2x)$This?

6. saifoo.khan

Pretty late though. @yummydum

7. yummydum

uff acha bhai mein chali jaati hoon..khush?

8. RolyPoly

You have to use chain rule for the second term lol

9. saifoo.khan

Yes! @RolyPoly I got till: $uv'+vu'$$\sin x(-2\sin(2x))+ \cos(2x)(\cos x)$

10. saifoo.khan

@yummydum : RUKO! Sath chalte hain. ;)

11. yummydum

kahan leja rahe ho?

12. saifoo.khan

In the second term? is my working correct? @RolyPoly

13. RolyPoly

Yes, I think so..

14. saifoo.khan

Jehan aap farmaish karain. @yummydum

15. saifoo.khan

What will the step after that? I'm stuck till there. @RolyPoly

16. technofable

yea it's right

17. RolyPoly

sin2x = 2sinxcosx cos2x= 2(cosx)^2 -1

18. RolyPoly

$=-2\sin x\sin(2x)+ \cos(2x)(\cos x)$$=-2\sin x(2\sin x \cos x)+ (2cos^2x-1)(\cos x)$

19. RolyPoly

For the first term, you'll get -4(sinx)^2 cosx (sinx)^2 = 1-(cosx)^2

20. RolyPoly

Then you can express it in terms of cosx, if that's what you want.

21. saifoo.khan

Ohhh. Right. Thanks @RolyPoly and @technofable

22. saifoo.khan

idk what does that mean.. @yummydum Dubai chaltay hain. =D

23. RolyPoly

Welcome..

24. yummydum

nahi yaar bus pakistan lejao phir tum free

25. saifoo.khan

Haha. Done. Kab chalna hai? @yummydum

26. yummydum

bus $2,000 mujhe de do baki sub khair hai, mein khud khayal kar loongi ...free biryani as a compliment ;) 27. saifoo.khan Lmao.$2000 ki tou main zindagi bhar ki biryani kha sakta hoon. :P @yummydum

28. yummydum

\$2000 main mein pakistan jaa sakti hoon aur shopping bhi poori....us mein se agar bacha tou tumhe biryani khiladoon gi :P

29. saifoo.khan

No thank you. Tumhari tokri main hole hoga, but Allah ka shukr mairi tokri main nahi hai.

30. yummydum

haha..chalo jao tum dubai chale jao..uri ko saath le jana :P

31. saifoo.khan

Lmao. Tum bhi chalo naa.

32. yummydum

mein tumhari kya lagti? :P

33. saifoo.khan

Uri mairi kia lagti?

34. yummydum

mein kya jaanoon? :P i dont go into private files

35. saifoo.khan

Hahaha. Aisa kabhi ho sakta hai k koi larki kabhi private files main na jaye?!

36. yummydum

LMAOO

37. yummydum

i respect private/personal space

38. saifoo.khan

Oh please. No girl is like that. I can list million of examples.

39. saifoo.khan

And since you belong to the same race, you can't be one. =D

40. yummydum

exactly why i tell you im different...sunnay ko taiyaar nahi ho, i know, but still its true :P

41. yummydum

to be a girl is not a race..its a species :P

42. saifoo.khan

OMG! EVERY OTHER girl EVERY OTHER says that she's not like "other girls" . Lol And you're saying the same thing!

43. yummydum

im not "like other girls"...im just not like girls at all :P

44. saifoo.khan

Wait! You're not like girls? Then? Are you like boys? lmao.

45. yummydum

tom boy

46. yummydum

acha ji mujhay kaam kerna hai, kisi aur ko dhoondo yeh sab bak bak kernay k liye :P

47. saifoo.khan

Haan haan. "larkon walay" kaam karnay hongay. :P Jao bhai. Kaam karo.

48. yummydum

if school work is "larkon walay kaam" then yes :P

49. saifoo.khan

Bhahiyon ki tarhan speed main kaam kia hai bhai apnay. Hats off.

50. yummydum

LOL

51. saifoo.khan

Haan waisay bhi larkiyan konsa parti hain.. Unhain ultay seedhay kaamon say fursay milaygi tou parhnay ka sochainge. :P

52. yummydum

uff itni nafrat lol :P

53. saifoo.khan

Lol. Not nafrat. Facts. Mairi konsa larkiyon say koi dushmani hai? ;D

54. yummydum

abhi nahi hai..jab shaadi ho jaegi tou phir poochna khud say k ab kuch nafrat hai ya nahi ;P

55. saifoo.khan

Nahi nahi, InshAllah aisa kuch nahi hoga. "She and I will live happily ever after <3". Lagta hai tumhain bara experience hai. 2-3 shadiyan kar chuki ho kia?

56. yummydum

LOLOLOLOLOL

57. yummydum

good to hear tum mein insaaniat hai :P

58. saifoo.khan

Alhamdulliah, achi wali hai. Tumhara husband jald suicide kar laiga. Tension na lo. :p

59. yummydum

Kaminay!

60. saifoo.khan

Haha. Aisa usko baar baar bologi tou aur jaldi kar laiga. ;D

61. yummydum

dont worry tumhari wali mere wale se pehli khudkushi kerlaigi :P

62. yummydum

ye shaadi hui nahi k time for funeral :P

63. saifoo.khan

Nah. Mairay sath itni khushi hogi k usko suicide ki zaroorat he nahi paregi.

64. yummydum

uff

65. saifoo.khan

Wait! Are you even going to get married? I doubt it.

66. saifoo.khan

MashAllah MashAllah. ;D

67. yummydum

abhi nahi for sure :P ...ill wait till im in my 20's...kaafi time para hai :D

68. yummydum

tumhara to lag raha hai kal shaadi hai :P

69. saifoo.khan

5~ saal tou hain. Tayyari start kardo! I wish. Ho jaye tou bohat he acha hai. ;D

70. yummydum

why so ready to get married? :P

71. yummydum

aur ji nahi abhi kuch 6-7 saat hein mere paas :)

72. saifoo.khan

Why shouldn't i be? aagay ka time kisne daikha hai? Hum rahain na rahain. ;D If you know what i mean.. Haha, haan haan.. pooray 20 saal he karlo. :p

73. yummydum

no i dont know what you mean...?

74. saifoo.khan

Like kia pta after 5-6 years you are alive or not. Phehlay karo, baad main karo karni tou hai he na. Tou for safety precautions, phehlay he karlo. Time bachao. :D

75. yummydum

LOL ...sahi

76. saifoo.khan

Ikr. Sahi like always. Ab nazar na lagao.

77. yummydum

nazar bhoolo ab thappar pare ga :P

78. saifoo.khan

I would love to get a thappar. ;D

79. saifoo.khan

Or thappars..

80. yummydum

kyun?

81. saifoo.khan

Why not? Thappar he tou hai.

82. saifoo.khan

But wait! Don't even dare to touch me. Mujhay koi deadly disease nahi lagwani.

83. yummydum

zor ka parta hai, soch lo? ...khair get used to it..jo aegi wo khud bohot mare gi :P

84. yummydum

mujhay koi zarurat nahi hai tumse disease lene ki so dont worry...tumhari jo aegi (agar aegi :P) wo khud mera kaam poora kerday gi

85. saifoo.khan

Haan haan. No worries. Bohat zoor zoor walay khaye hain.. Aur tumhara tou simple hai.. Haha. Disease mujhay lagay gi TUM say. InshAllah ayegi. And aisa koi kaam pura nahi karnay wali wo.

86. yummydum

uff..chalo ro nahi :P ...i have to go..tum jao usse dhoodo ;P

87. saifoo.khan

Haha. I'm going too. Nite. :')