Trigonometry Limits: Solving lim x -> 0 sin x / sin(x/2)

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SUMMARY

The limit of the expression lim x -> 0 (sin x / sin(x/2)) is conclusively determined to be 2. This conclusion is reached by recognizing that sin(2(x/2)) approaches twice the value of sin(x/2) as x approaches zero. An alternative approach using L'Hospital's Rule or the double angle formula sin(2a) = 2sin(a)cos(a) can also be applied to derive the same result, simplifying the expression to (2sin(x/2)cos(x/2)) / sin(x/2).

PREREQUISITES
  • Understanding of limits in calculus
  • Familiarity with trigonometric functions and their properties
  • Knowledge of L'Hospital's Rule
  • Ability to apply the double angle formula for sine
NEXT STEPS
  • Study the application of L'Hospital's Rule in limit problems
  • Explore the double angle formulas for trigonometric functions
  • Practice solving limits involving trigonometric functions
  • Review the behavior of sine functions near zero
USEFUL FOR

Students studying calculus, particularly those focusing on limits and trigonometric functions, as well as educators seeking to enhance their teaching methods in these areas.

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Homework Statement



Find lim x -> 0 [tex]\frac{sin x}{sin\frac{x}{2}}[/tex]

The Attempt at a Solution



Since period of sin 2(x/2) is T/2 compared to period T of sin (x/2)

sin 2(x/2) nears twice the value of sin (x/2) for all values of x approaching zero.

Therefore lim x -> 0 [tex]\frac{sin x}{sin\frac{x}{2}}[/tex] = 2

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somehow i find the reasoning flawed, anyone can offer a better solution?
 
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Did you think to try L'Hospital's Rule?
 
if you don't want to use Calculus (though this is in the Calculus section!), use the double angle formula, sin(2a)= 2 sin(a)cos(a) to write this as
[tex]\frac{2sin\left(\frac{x}{2}\right)cos\left(\frac{x}{2}\right)}{sin\left(\frac{x}{2}\right)}[/tex]
 

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