Differentiate!

• secretliker

  10 Apr 08, 21:44

  Help me differentiate!! d/dx [(1 + cos x) / sin x ] Thanks ^^
• eagle

  10 Apr 08, 21:58

  = d/dx (cosec x + cot x)

  = -cosec x cot x - (cosec x)^2

   

  Edit: Properties here

• secretliker

  10 Apr 08, 22:20

  (see below)

  Is there anything wrong? My answer is different from the answer key!

• secretliker

  10 Apr 08, 22:29

  

• eagle

  10 Apr 08, 22:37

  Originally posted by secretliker:

  

  Same answer if you change the denominator to sin^2, but rather inefficient. Why not do it in just 2 lines?

  I hv added a link to the above post.

• eagle

  10 Apr 08, 22:38

  Originally posted by secretliker:

  (see below)

  Is there anything wrong? My answer is different from the answer key!

  what is the answer key... trigo functions can be expressed differently....

  may I know which level you are at?

• secretliker

  10 Apr 08, 22:44

  1 / (1 - cos x)

  I'm helping my brother who's in Sec 4.

• eagle

  10 Apr 08, 22:55

  Originally posted by secretliker:

  1 / (1 - cos x)

  I'm helping my brother who's in Sec 4.

  u can simply

  -(1+cos x) / (1-cos^2 x)
  - (1+cos x) / [(1+cosx)(1-cos x)]
  - 1 / (1 - cos x)

  Do check if the minus sign is there

• secretliker

  10 Apr 08, 23:02

  Thanks eagle! I overlooked the a^2 - b^2 = (a+b)(a-b) thing. No wonder I can't get it.

  Yes, there's minus sign.

• hiphop2009

  11 Apr 08, 00:58

  gosh eagle is godly~.

  a round of applause~~...

  i only thinking how to solve when he can get it all right.

• eagle

  11 Apr 08, 10:20

  nah... I think I will forget most stuff in a few years time

  So now while I still remember some, I try to help whenever possible...

• FirePig

  11 Apr 08, 21:09

  Originally posted by hiphop2009:

  i only thinking how to solve when he can get it all right.

  
  only needs 2 steps to solve...