Finding a limit of a sequence or proving it diverges

  • Thread starter Thread starter nikolafmf
  • Start date Start date
  • Tags Tags
    Limit Sequence
Click For Summary
The sequence defined as sin(1), cos(sin(1)), sin(cos(sin(1))) is examined for convergence or divergence. To prove divergence, it is suggested to find two subsequences that converge to different limits, but this approach proves challenging. It is established that if the sequence converges to a limit L, it must satisfy the equations sin(L) = L and cos(L) = L. The conclusion drawn from these equations is that the sequence diverges. Overall, the discussion emphasizes the relationship between the sequence's behavior and the properties of sine and cosine functions.
nikolafmf
Messages
112
Reaction score
0

Homework Statement



Given is a sequence: sin(1), cos(sin(1)), sin(cos(sin(1))) etc. Find the limit of the sequence or prove it diverges.

Homework Equations



?

The Attempt at a Solution



One way to prove a sequence diverges is to find two subsequences which converge to different limits, but I could not find such. I would be thankful for any idea :)
 
Physics news on Phys.org
nikolafmf said:

Homework Statement



Given is a sequence: sin(1), cos(sin(1)), sin(cos(sin(1))) etc. Find the limit of the sequence or prove it diverges.


Homework Equations



?

The Attempt at a Solution



One way to prove a sequence diverges is to find two subsequences which converge to different limits, but I could not find such.


I would be thankful for any idea :)

If there is a limit L, then it must satisfy both sin(L)=L and cos(L)=L, mustn't it?
 
Suppose it does converge to some value. What equations could you deduce regarding that value?
[Dick beat me to the Submit, and was a little more generous with the hint.]
 
haruspex said:
Suppose it does converge to some value. What equations could you deduce regarding that value?
[Dick beat me to the Submit, and was a little more generous with the hint.]

Yeah, probably too generous in retrospect. I like yours better as a starter hint.
 
Last edited:
Yes, it is true, it must satisfy both sin(L)=L and cos(L)=L, from which follows that the sequence diverges :)

Thank you very much to both for the help :)
 

Similar threads

Replies
16
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 5 ·
Replies
5
Views
1K
  • · Replies 1 ·
Replies
1
Views
4K
  • · Replies 4 ·
Replies
4
Views
1K
Replies
8
Views
987
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 10 ·
Replies
10
Views
2K