Chapter 24: Problem 25
Let \(f(x)=\left(\sin \left(\tan ^{-1} x\right)+\sin \left(\cot ^{-1} x\right)\right)^{2}-1,|x|>1\). If \(\frac{d y}{d x}=\frac{1}{2} \frac{d}{d x}\left(\sin ^{-1}(f(x))\right)\) and \(y(\sqrt{3})=\frac{\pi}{6}\), then \(y(-\sqrt{3})\) is equal to: (a) \(\frac{2 \pi}{3}\) (b) \(-\frac{\pi}{6}\) (c) \(\frac{5 \pi}{6}\) (d) \(\frac{\pi}{3}\)
Short Answer
Step by step solution
Simplify the function f(x)
Evaluate the inverse sine of f(x)
Differentiate the expression with respect to x
Solve the Differential Equation
Apply Initial Conditions and Solve for y(-√3)
Conclusion
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Inverse Trigonometric Functions
These functions are used to find the angle that corresponds to a given sine, cosine, or tangent value.
In our problem, we deal with \( \tan^{-1} x \) and \( \cot^{-1} x \). Understanding the geometry behind inverse trigonometric functions is key.
For \( \tan^{-1} x \), if \( \theta = \tan^{-1} x \), then \( \tan \theta = x \), which points us to a right triangle with \( x \) as opposite and \( 1 \) as adjacent.
This leads us to calculate \( \sin(\tan^{-1}x) \) using a triangle's property.
- \( \sin(\theta) = \frac{x}{\sqrt{x^2+1}} \)
- \( \cos(\theta) = \frac{1}{\sqrt{x^2+1}} \)
This helps derive \( \sin(\cot^{-1}x) \), important for the function studdied in this exercise.
Function Simplification
In this exercise, we simplified the function \( f(x) = (\sin(\tan^{-1} x) + \sin(\cot^{-1} x))^2 - 1 \).
Initially, it involves calculating \( \sin(\tan^{-1} x) \) and \( \sin(\cot^{-1} x) \) based on trigonometric principles.
- By substituting \( \sin(\tan^{-1} x) = \frac{x}{\sqrt{x^2+1}} \) and \( \sin(\cot^{-1} x) = \frac{1}{\sqrt{x^2+1}} \) back into the expression, the function simplifies to \( \frac{x+1}{\sqrt{x^2+1}} \).
- Squaring this results in \( \frac{(x+1)^2}{x^2+1} \), and simplifying further leads to \( f(x) = \frac{2x}{x^2+1} \).
Derivative Calculation
In this exercise, the derivative of the function \( y \) with respect to \( x \) was calculated, where \( \frac{dy}{dx} = \frac{1}{2} \frac{d}{dx}(\sin^{-1}(f(x))) \).
The process relies on the chain rule as well as understanding derivatives of inverse functions.For the derivative of \( \sin^{-1}(f(x)) \):
- The derivative of \( \sin^{-1}(u) \) is \( \frac{1}{\sqrt{1-u^2}} \cdot \frac{du}{dx} \).
- Inserting \( f(x) = \frac{2x}{x^2+1} \), we calculate \( \frac{d}{dx}(f(x)) = \frac{2(1-x^2)}{(x^2+1)^2} \).
This process emphasizes the importance of the derivative in connecting function behavior to real-world scenarios, essential in this calculus exercise.