Chapter 4: Problem 52
Find the linear approximation \(L(x)\) to \(y=f(x)\) near \(x=a\) for the function. \(f(x)=\tan x, a=\frac{\pi}{4}\)
Short Answer
Expert verified
The linear approximation is \( L(x) = 2x + 1 - \frac{\pi}{2} \) near \( x = \frac{\pi}{4} \).
Step by step solution
01
Find the Value of the Function at the Point
To find the linear approximation of the function near a point, we first need to evaluate the function at that point. Here, the function is \( f(x) = \tan x \) and we need to evaluate it at \( x = \frac{\pi}{4} \). Since \( \tan \left( \frac{\pi}{4} \right) = 1 \), we find that \( f \left( \frac{\pi}{4} \right) = 1 \).
02
Calculate the Derivative of the Function
The next step is to find the derivative of the function, \( f'(x) \). For \( f(x) = \tan x \), the derivative \( f'(x) = \sec^2 x \).
03
Evaluate the Derivative at the Given Point
Now, we need to evaluate the derivative at the point \( x = \frac{\pi}{4} \). We know that \( \sec \left( \frac{\pi}{4} \right) = \sqrt{2} \), so \( \sec^2 \left( \frac{\pi}{4} \right) = 2 \). Thus, \( f' \left( \frac{\pi}{4} \right) = 2 \).
04
Formulate the Linear Approximation Formula
The linear approximation, \( L(x) \), is given by the formula \( L(x) = f(a) + f'(a)(x - a) \). Plugging in our values: \( a = \frac{\pi}{4} \), \( f(a) = 1 \), and \( f'(a) = 2 \), we have \( L(x) = 1 + 2(x - \frac{\pi}{4}) \).
05
Simplify the Linear Approximation Expression
Simplify the linear approximation expression: \( L(x) = 1 + 2x - \frac{\pi}{2} \). Therefore, the linear approximation near \( x = \frac{\pi}{4} \) is \( L(x) = 2x + 1 - \frac{\pi}{2} \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Tangent Function
The tangent function, often represented as \( \tan x \), is a periodic function vital in trigonometry and calculus. This function takes an angle as input and returns the ratio of the sine and cosine of that angle, \( \tan x = \frac{\sin x}{\cos x} \). It is important to note:
- The tangent function has a period of \( \pi \). This means that every \( \pi \) units along the \( x \)-axis, the function repeats its values.
- The function is undefined at odd multiples of \( \frac{\pi}{2} \), as the cosine in the denominator equals zero at these points.
- Tangent is often used in various fields such as engineering, physics, and computer science for modeling cyclical phenomena.
Derivative Evaluation
Derivative evaluation is a fundamental concept in calculus that involves determining the instantaneous rate of change of a function with respect to one of its variables. Mathematically, if \( f(x) \) is our function, the derivative, \( f'(x) \), measures how \( f(x) \) changes as \( x \) changes.
- For the tangent function, \( f(x) = \tan x \), its derivative is \( f'(x) = \sec^2 x \), a significant result in calculus.
- The symbol \( \sec x \) represents the secant function, given by \( \sec x = \frac{1}{\cos x} \).
Linearization Formula
The linearization formula is a powerful tool in calculus used to approximate the value of a function near a given point. It is derived from the tangent line equation and provides an easier way to estimate function values. The general linearization formula is given by:
- \( L(x) = f(a) + f'(a)(x-a) \)
- \( f(a) \) is the function's value at the point \( a \).
- \( f'(a) \) is the derivative at \( a \).
- \( x-a \) represents a small change from the point \( a \).
Calculus
Calculus is a core area of mathematics centered around change and motion. It encompasses two main branches: differential calculus and integral calculus. Each provides unique methods for analyzing and understanding various phenomena.
- Differential calculus is the part dealing with the concept of a derivative. It focuses on understanding and calculating the rate of change of quantities.
- Integral calculus focuses on accumulation and areas under curves, putting together pieces to form a complete picture.