Require help understanding small angle approximation

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SUMMARY

The discussion focuses on the small angle approximation in physics, specifically the approximation of sinθ and tanθ by θ in radians. The user seeks to determine the values of θ where the error in these approximations is approximately 5%. The error is calculated using the formula |sinθ - θ| / |sinθ|, which quantifies the percentage difference between sinθ and θ. The user successfully resolves the initial confusion regarding the application of this formula and arrives at the correct answers for the specified angles.

PREREQUISITES
  • Understanding of trigonometric functions, specifically sin and tan.
  • Familiarity with radians and degree measurements.
  • Basic knowledge of error analysis in mathematical approximations.
  • Ability to manipulate and solve inequalities involving trigonometric functions.
NEXT STEPS
  • Explore the derivation of the small angle approximation for sin and tan functions.
  • Learn how to apply Taylor series expansions for trigonometric functions.
  • Investigate error analysis techniques in numerical methods.
  • Study the implications of small angle approximations in wave physics and optics.
USEFUL FOR

Students in physics or mathematics, educators teaching trigonometry, and anyone interested in understanding approximations in physical problems.

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Homework Statement


"In order to simplify problems in physics, we often use various approximations. For example, when we investigate diffraction and interference patterns at small angles θ, we frequently approximate sinθ and tanθ by θ (in radians). Here you will calculate over what range these are reasonable approximations.

For θ= 43° this approximation has an error of almost exactly 10%:

θ = 43.0° = 0.75 radians

sinθ=0.682

|sinθ-θ| / |sinθ| ≈ 10%"

1) For what value of θ (to the nearest degree) is the error in sinθ ≈ θ approximately 5%?
2) For what value of θ (to the nearest degree) is the error in tanθ ≈ θ approximately 5%?

I was recently given this question and very little explanation of the concept. I've struggled with this for a week and read absolutely everything I can find and I'm still not any closer to understanding it. Can anyone please point me in the right direction or explain how to do question 1) and 2)? There are many more questions, but if I can get 1) and 2) down then I should be able to answer the rest by myself. I appreciate any help.

Homework Equations


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The Attempt at a Solution


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The equation at the end explains that |sinθ-θ|/|sinθ| gives the error in approximating sinθ by θ. In other words, it gives the percentage which theta differs from sinθ.

The first question asks: For what values of theta does theta differ from sinθ by less than 5%? in other words:
\displaystyle \frac{|sinθ-θ|}{|sinθ|}≤.05
 
Nessdude14 said:
The equation at the end explains that |sinθ-θ|/|sinθ| gives the error in approximating sinθ by θ. In other words, it gives the percentage which theta differs from sinθ.

The first question asks: For what values of theta does theta differ from sinθ by less than 5%? in other words:
\displaystyle \frac{|sinθ-θ|}{|sinθ|}≤.05


Thank you, I had been using the equation incorrectly without realising. I have the correct answers now.
 

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