Math Problem Statement

lim x→0 (1 - cos^2(2x)) / (2x)^2

Solution

The limit presented in the image is:

limx01cos2(2x)(2x)2\lim_{x \to 0} \frac{1 - \cos^2(2x)}{(2x)^2}

We can simplify and solve this limit step-by-step.

Step 1: Use a trigonometric identity

We know the identity 1cos2(θ)=sin2(θ)1 - \cos^2(\theta) = \sin^2(\theta). Applying this to the numerator:

1cos2(2x)=sin2(2x)1 - \cos^2(2x) = \sin^2(2x)

So the limit becomes:

limx0sin2(2x)(2x)2\lim_{x \to 0} \frac{\sin^2(2x)}{(2x)^2}

Step 2: Simplify the expression

We now rewrite the expression as:

limx0(sin(2x)2x)2\lim_{x \to 0} \left( \frac{\sin(2x)}{2x} \right)^2

Step 3: Use the standard limit

We know from standard calculus that:

limx0sin(x)x=1\lim_{x \to 0} \frac{\sin(x)}{x} = 1

So, applying this to sin(2x)2x\frac{\sin(2x)}{2x}:

limx0(sin(2x)2x)2=12=1\lim_{x \to 0} \left( \frac{\sin(2x)}{2x} \right)^2 = 1^2 = 1

Final Answer:

limx01cos2(2x)(2x)2=1\lim_{x \to 0} \frac{1 - \cos^2(2x)}{(2x)^2} = 1

Would you like any further details or explanations on this solution?

Here are 5 related questions to expand your understanding:

  1. How does the limit of sin(x)x\frac{\sin(x)}{x} help in solving other trigonometric limits?
  2. What other trigonometric identities can be applied to simplify limits?
  3. How would the limit change if we were using a different trigonometric function, such as tan(x)\tan(x)?
  4. What are common standard limits used in calculus, and why are they important?
  5. How do you handle indeterminate forms like 00\frac{0}{0} in limits?

Tip: Always check for trigonometric identities when dealing with limits involving trigonometric functions—they can simplify the problem significantly!

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Math Problem Analysis

Mathematical Concepts

Calculus
Limits
Trigonometry

Formulas

1 - cos^2(θ) = sin^2(θ)
lim x→0 (sin(x)/x) = 1

Theorems

Limit Theorems
Trigonometric Identities

Suitable Grade Level

Grades 11-12