Finding the Limit of Trig Functions: 2x/sin3x, x->0

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SUMMARY

The limit of the function 2x/sin(3x) as x approaches 0 is definitively calculated as 2/3. This conclusion is reached by applying the fundamental limit lim sin(x)/x = 1, which simplifies the expression to lim 2/3 (sin(x)/x) as x approaches 0. The discussion confirms that rewriting the limit as 2/3 (3x)/sin(3x) clarifies the evaluation process, ensuring accuracy in the solution.

PREREQUISITES
  • Understanding of limits in calculus
  • Familiarity with the limit property lim sin(x)/x = 1
  • Basic algebraic manipulation of functions
  • Knowledge of trigonometric functions and their behavior near zero
NEXT STEPS
  • Study the application of L'Hôpital's Rule for indeterminate forms
  • Explore advanced limit techniques involving trigonometric functions
  • Learn about Taylor series expansions for sin(x) near x=0
  • Investigate the concept of continuity and differentiability in calculus
USEFUL FOR

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

domyy
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Homework Statement



lim 2x/(sin3x)
x-> 0

Homework Equations



lim sinx/x = 1
x->0

The Attempt at a Solution



is it correct to say the following:

lim 2/3 (sinx/x)
x-> 0

lim 2/3 (1)
x-> 0

Answer: lim 2x/sin3x = 2/3
x-> 0

Because it's on the book:
cos 2x(2)/3 = 2/3
x->0

So I want to know if I solve it the way I did before, would it be correct?
 
Last edited:
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domyy said:

Homework Statement



lim 2x/(sin3x)
x-> 0


Homework Equations



lim sinx/x = 1
x->0

The Attempt at a Solution



is it correct to say the following:

lim 2/3 (sinx/x)
x-> 0

lim 2/3 (1)
x-> 0

Answer: lim 2x/sin3x = 2/3
x-> 0

Because it's on the book:
cos 2x(2)/3 = 2/3
x->0

So I want to know if I solve it the way I did before, would it be correct?

lim 2/3 sin(x)/x is zero at x=0, but 2x/sin(3x) is not the same as (2/3)sin(x)/x.

Rewrite 2x/sin(3x) as 2/3 (3x)/sin(3x).

ehild
 
Thanks! Got it! =)
 

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