Chapter 5: Problem 5
Find the average value of the function over the given interval. $$ f(x)=\sin x ;[0, \pi] $$
Short Answer
Expert verified
The average value is \( \frac{2}{\pi} \).
Step by step solution
01
Understand the Average Value Formula
The average value of a continuous function \( f(x) \) over the interval \([a, b]\) is given by the formula: \[ \text{Average Value} = \frac{1}{b-a} \int_{a}^{b} f(x) \, dx \] In this case, \( f(x) = \sin x \), \( a = 0 \), and \( b = \pi \).
02
Set Up the Integral
Using the average value formula, set up the integral: \[ \text{Average Value} = \frac{1}{\pi - 0} \int_{0}^{\pi} \sin x \, dx \] This simplifies to: \[ \frac{1}{\pi} \int_{0}^{\pi} \sin x \, dx \]
03
Integrate the Function
Integrate \( \sin x \) from \( 0 \) to \( \pi \). The antiderivative of \( \sin x \) is \(-\cos x\). Therefore, \[ \int_{0}^{\pi} \sin x \, dx = [-\cos x]_{0}^{\pi} \]
04
Evaluate the Definite Integral
Substitute the limits into the antiderivative: \[ -\cos(\pi) - (-\cos(0)) \] Knowing that \( \cos(\pi) = -1 \) and \( \cos(0) = 1 \), we get: \[ -(-1) - (-1) = 1 + 1 = 2 \]
05
Calculate the Average Value
Substitute the result back into the average value formula: \[ \frac{1}{\pi} \times 2 = \frac{2}{\pi} \] Therefore, the average value of the function \( f(x) = \sin x \) over the interval \([0, \pi]\) is \( \frac{2}{\pi} \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Integration
Integration is a fundamental concept in calculus, which helps in finding the accumulation of quantities, such as area under curves. When we talk about integrating a function, we refer to finding its antiderivative or integral.
- An integral can be indefinite, representing a family of functions, or definite, which involves a specific calculation over an interval.
- In this case, we work with definite integrals as it calculates the average value of a function over an interval.
Definite Integral
A definite integral computes the net area under a curve defined by a function, over a specified interval. This is expressed as \( \int_{a}^{b} f(x) \, dx \), where \( a \) and \( b \) are the interval's bounds.
- In our exercise, \( a = 0 \) and \( b = \pi \).
- The definite integral tells us how much area exists between the function and the x-axis from \( x = 0 \) to \( x = \pi \).
- To solve it, we first find the antiderivative of \( f(x) = \sin x \).
Trigonometric Functions
Trigonometric functions relate angles to the sides of a triangle and are foundational in both algebra and calculus. In calculus, we often deal with functions like \( \sin x \), \( \cos x \), and \( \tan x \).
- These functions are essential in calculating integrals and derivatives.
- The sine function, \( \sin x \), oscillates between \(-1\) and \(1\), making it vital for modeling wave-like phenomena.