Chapter 3: Problem 11
In Exercises \(11-14\) , find the linearization of \(f\) at \(x=a\) . Then graph the linearization and \(f\) together. $$ f(x)=\sin x \quad \text { at } \quad(\text { a }) x=0, \quad \text { (b) } x=\pi $$
Short Answer
Expert verified
Linearization at \( x=0 \) is \( x \); at \( x=\pi \) is \( \pi-x \).
Step by step solution
01
Understand the Problem
The problem asks us to find the linearization of the function \( f(x) = \sin x \) at two points, \( x = 0 \) and \( x = \pi \). Linearization involves finding the tangent line to the curve at a given point.
02
Determine the Derivative
To find the linearization, we first need the derivative of \( f(x) = \sin x \). The derivative is \( f'(x) = \cos x \). This derivative will help calculate the slope of the tangent line at any given point.
03
Calculate the Tangent Line at \( x=0 \)
For the point \( x=0 \), compute the function value \( f(0) = \sin 0 = 0 \) and the derivative \( f'(0) = \cos 0 = 1 \). The equation of the tangent line (linearization) at \( x=0 \) is found using the point-slope form: \( L(x) = f(a) + f'(a)(x-a) \). Thus, \( L(x) = 0 + 1(x-0) = x \).
04
Calculate the Tangent Line at \( x=\pi \)
For the point \( x=\pi \), compute the function value \( f(\pi) = \sin \pi = 0 \) and the derivative \( f'(\pi) = \cos \pi = -1 \). The equation of the tangent line at \( x=\pi \) becomes \( L(x) = 0 - 1(x-\pi) = \pi - x \).
05
Graph \( f(x) \) and Linearizations
Plot the original function \( f(x) = \sin x \) and the linearizations \( L(x) = x \) at \( x = 0 \) and \( L(x) = \pi - x \) at \( x = \pi \) on the same graph. The linearizations should appear as tangent lines to the curve at the specified points.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Linearization
Linearization is a method used in calculus to approximate a complex function with a simple linear one. It is particularly helpful when you want to make quick predictions without complex calculations. The technique involves creating a tangent line at a specific point of a function. This tangent line approximates how the function behaves near that point. To linearize a function at a point, you use the formula for the tangent line:
- \[ L(x) = f(a) + f'(a)(x-a) \]
Trigonometric Functions
Trigonometric functions, like sine and cosine, are used to describe the relationships of angles in right-angled triangles and periodic phenomena. In the given exercise, we deal with the function \( f(x) = \sin x \). Sine function attributes:
- The sine function ranges from -1 to 1.
- The sine wave repeats every \( 2\pi \).
- Key points include: \( \sin 0 = 0 \), \( \sin \frac{\pi}{2} = 1 \), \( \sin \pi = 0 \).
Tangent Line
A tangent line is a straight line that just touches a curve at one point. It represents the instantaneous direction or slope of the curve at that specific point. For effective linearization, this tangent line acts as the best straight-line approximation to a curve near a given point.In the exercise, we used tangent lines to approximate \( \sin x \) at \( x = 0 \) and \( x = \pi \):
- At \( x = 0 \), the tangent line was \( L(x) = x \).
- At \( x = \pi \), it became \( L(x) = \pi - x \).
Derivative
The derivative of a function tells us about the rate at which one quantity changes with respect to another. It is crucial for finding the slope of a tangent line, which is used in the linearization process.To linearize \( f(x) = \sin x \), we need its derivative \( f'(x) = \cos x \). This derivative function gives us the slope of the sine function at any point \( x \):
- At \( x = 0 \), the slope is \( f'(0) = \cos 0 = 1 \).
- At \( x = \pi \), the slope is \( f'(\pi) = \cos \pi = -1 \).