What is the solution to this trigonometric limit problem?

Click For Summary
SUMMARY

The limit problem presented is to find \(\lim_{x \to 0}\frac{1-\cos(x)\cos(2x)\cos(3x)}{1-\cos(x)}\). The solution involves rewriting the numerator using the identity \(\lim_{x \to 0}\frac{1-\cos(x)+\cos(x)[1-\cos(2x)+\cos(2x)(1-\cos(3x)]}{1-\cos(x)}\). This transformation simplifies the limit and reveals the underlying relationships between the cosine functions. The key insight is recognizing the addition and subtraction of \(\cos(x)\) in the numerator as a critical step in solving the limit.

PREREQUISITES
  • Understanding of trigonometric limits
  • Familiarity with the cosine function and its properties
  • Knowledge of limit laws and algebraic manipulation
  • Ability to expand trigonometric identities
NEXT STEPS
  • Study the derivation of trigonometric limits using Taylor series expansions
  • Learn about L'Hôpital's Rule for evaluating indeterminate forms
  • Explore the properties of cosine functions and their behavior near zero
  • Practice solving similar limit problems involving trigonometric functions
USEFUL FOR

Students studying calculus, particularly those focusing on limits and trigonometric functions, as well as educators looking for examples of limit evaluation techniques.

chmate
Messages
37
Reaction score
0

Homework Statement



Find \lim_{x \to 0}\frac{1-cosxcos2xcos3x}{1-cosx}

The Attempt at a Solution



Actually my book gives this continuation \lim_{x \to 0}\frac{1-cosx+cosx[1-cos2x+cos2x(1-cos3x)]}{1-cosx} but I don't know how author arrived there. Can anyone explain it to me?

Thank you
 
Last edited:
Physics news on Phys.org
The author rewrote the numerator; if you expand all brackets, you arrive at the same expression.
 
Yeah, I realized, after I posted this thread, that author added and substracted cosx in numerator. This was the trick.

The problem is solved.
 

Similar threads

Replies
5
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 10 ·
Replies
10
Views
1K
Replies
4
Views
2K
Replies
10
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 10 ·
Replies
10
Views
2K
  • · Replies 36 ·
2
Replies
36
Views
6K