• Support PF! Buy your school textbooks, materials and every day products Here!

Hard C3 question

  • Thread starter thomas49th
  • Start date
  • #1
655
0
File0007.jpg


im stuck on the top question on part B

i can do the difference of 2 squares on the LHS but how do i get rid of the cosec²x - cot²x ??

Thanks
 

Answers and Replies

  • #2
1
0
mis-post, oops!

Edit: Well, as I'm here...

[itex]cosec^2\theta - cot^2\theta = 1[/itex]
[itex]cosec^2\theta + cot^2\theta = -1[/itex]

Well, that's the RHS...

[itex]-cot^4\theta = -cot^2\theta \times cot^2\theta\newline[/itex]
[itex]= (1 - cosec^2\theta)(cosec^2\theta - 1)\newline[/itex]
[itex]= -1 + cosec^2\theta - cosec^4\theta - cosec^2\theta\newline[/itex]


Back to the original question!

[itex]cosec^4\theta - cosec^4\theta - 1 = - 1\newline[/itex]
[itex]-1 = -1[/itex]


I think that's correct :S

(Hmm, latex is messed up, how do I make a newline?)
 
Last edited:
  • #3
Gib Z
Homework Helper
3,346
4
Use the result in part a) like it told you to.
 
  • #4
D H
Staff Emeritus
Science Advisor
Insights Author
15,393
682
3lliot, please do not give out answers. We offer free help here at PF, not free answers.
 

Related Threads for: Hard C3 question

  • Last Post
Replies
1
Views
3K
  • Last Post
Replies
2
Views
4K
Replies
3
Views
796
  • Last Post
Replies
10
Views
2K
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
3
Views
742
  • Last Post
Replies
10
Views
4K
Top