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Ch. 5 - Integration
Briggs - Calculus: Early Transcendentals 3rd Edition
Briggs3rd EditionCalculus: Early TranscendentalsISBN: 9780136847243Not the one you use?Change textbook
Chapter 5, Problem 5.4.18

Symmetry in integrals Use symmetry to evaluate the following integrals.
∫₋π/₂^π/² 5 sin θ dθ

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Recognize that the integral involves a symmetric interval about zero: [-π/2, π/2]. This symmetry can simplify the evaluation process.
Observe the integrand, 5 sin(θ). The function sin(θ) is odd, meaning sin(-θ) = -sin(θ). This property is crucial for determining the behavior of the integral over symmetric intervals.
Use the property of odd functions: When integrating an odd function over a symmetric interval about zero, the integral evaluates to zero. This is because the positive and negative contributions cancel each other out.
Conclude that the integral ∫₋π/₂^π/₂ 5 sin(θ) dθ equals zero due to the symmetry and the odd nature of sin(θ).
No further computation is needed, as the symmetry property directly provides the result.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Symmetry in Integrals

Symmetry in integrals refers to the property that allows certain integrals to be simplified based on the symmetry of the function being integrated. If a function is even (symmetric about the y-axis), the integral from -a to a can be computed as twice the integral from 0 to a. If the function is odd (symmetric about the origin), the integral over a symmetric interval around zero is zero.
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Trigonometric Functions

Trigonometric functions, such as sine and cosine, are fundamental in calculus, especially in integrals involving angles. The sine function, sin(θ), is periodic and has specific properties, such as being odd, which means sin(-θ) = -sin(θ). Understanding these properties is crucial for evaluating integrals that involve trigonometric functions.
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Definite Integrals

A definite integral calculates the area under a curve defined by a function over a specific interval [a, b]. It is represented as ∫_a^b f(x) dx and provides a numerical value. Evaluating definite integrals often involves techniques such as substitution, integration by parts, or leveraging symmetry, which can simplify the computation significantly.
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Related Practice
Textbook Question

Limits of sums Use the definition of the definite integral to evaluate the following definite integrals. Use right Riemann sums and Theorem 5.1.


∫₀² (2𝓍 + 1) d𝓍

Textbook Question

Displacement from velocity The following functions describe the velocity of a car (in mi/hr) moving along a straight highway for a 3-hr interval. In each case, find the function that gives the displacement of the car over the interval [0,t], where 0 ≤ t ≤ 3.

v(t) = { 30 if 0 ≤ t ≤ 2

50 if 2 < t < 2.5

44 if 2.5 < t ≤ 3

Textbook Question

Indefinite integrals Use a change of variables or Table 5.6 to evaluate the following indefinite integrals. Check your work by differentiating.                                                                                  

                                                                                                                                                                    

 ∫ sec² (10𝓍 + 7) d𝓍

Textbook Question

Definite integrals Evaluate the following integrals using the Fundamental Theorem of Calculus


∫₁² (z² + 4) / z dz

1
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Textbook Question

Definite integrals Evaluate the following integrals using the Fundamental Theorem of Calculus


∫₁² 3/t dt

Textbook Question

Definite integrals Use geometry (not Riemann sums) to evaluate the following definite integrals. Sketch a graph of the integrand, show the region in question, and interpret your result.


 ∫₀⁴ ƒ(𝓍) d𝓍, where ƒ(𝓍) = {5      if 𝓍 ≤ 2                                                                                                                                                                                     

                      3𝓍 ― 1  if 𝓍 > 2