Math Problem Statement

lim(θ → π/4) (sin(θ) - √2/2) / (θ - π/4)

Solution

The expression in the image is a limit problem, specifically:

limθπ4sin(θ)22θπ4\lim_{\theta \to \frac{\pi}{4}} \frac{\sin(\theta) - \frac{\sqrt{2}}{2}}{\theta - \frac{\pi}{4}}

To solve this, we observe that direct substitution of θ=π4\theta = \frac{\pi}{4} into the expression will lead to the indeterminate form 00\frac{0}{0}. This suggests that we can apply L'Hôpital's Rule, which helps solve limits that result in indeterminate forms.

Steps to solve:

  1. Differentiate the numerator: The numerator is sin(θ)22\sin(\theta) - \frac{\sqrt{2}}{2}. The derivative of sin(θ)\sin(\theta) is cos(θ)\cos(\theta).

  2. Differentiate the denominator: The denominator is θπ4\theta - \frac{\pi}{4}. The derivative of θ\theta is simply 1.

Now, apply L'Hôpital's Rule:

limθπ4sin(θ)22θπ4=limθπ4cos(θ)1\lim_{\theta \to \frac{\pi}{4}} \frac{\sin(\theta) - \frac{\sqrt{2}}{2}}{\theta - \frac{\pi}{4}} = \lim_{\theta \to \frac{\pi}{4}} \frac{\cos(\theta)}{1}

Substituting θ=π4\theta = \frac{\pi}{4}:

cos(π4)1=221=22\frac{\cos\left(\frac{\pi}{4}\right)}{1} = \frac{\frac{\sqrt{2}}{2}}{1} = \frac{\sqrt{2}}{2}

Final Answer:

limθπ4sin(θ)22θπ4=22\lim_{\theta \to \frac{\pi}{4}} \frac{\sin(\theta) - \frac{\sqrt{2}}{2}}{\theta - \frac{\pi}{4}} = \frac{\sqrt{2}}{2}

Would you like more details about how this rule works, or do you have other questions related to this topic?

Here are 5 related questions:

  1. What is the general form of L'Hôpital's Rule?
  2. Can limits like this one be evaluated using other methods besides L'Hôpital's Rule?
  3. How does cos(θ)\cos(\theta) behave near π4\frac{\pi}{4}?
  4. What is the geometric interpretation of this limit in terms of slopes?
  5. What happens if we apply this limit for other values of θ\theta?

Tip: L'Hôpital's Rule is a powerful tool for resolving limits that yield indeterminate forms like 00\frac{0}{0} or \frac{\infty}{\infty}.

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Math Problem Analysis

Mathematical Concepts

Limits
L'Hopital's Rule
Trigonometry

Formulas

lim(θ → a) (f(θ) / g(θ)) = lim(θ → a) (f'(θ) / g'(θ)) when lim(θ → a) f(θ) = lim(θ → a) g(θ) = 0

Theorems

L'Hopital's Rule

Suitable Grade Level

Grades 11-12