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Ch. 8 - Techniques of Integration
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077당신이 사용하는 게 아니라요?교과서 변경
8장, 문제 8.3.73

Volume: Find the volume generated by revolving one arch of the curve y = sin x about the x-axis.

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1
Identify the interval for one arch of the curve \( y = \sin x \). Since one arch corresponds to one complete wave from 0 to \( \pi \), set the limits of integration as \( x = 0 \) to \( x = \pi \).
Recall the formula for the volume \( V \) generated by revolving a curve \( y = f(x) \) about the x-axis from \( x = a \) to \( x = b \): \[ V = \pi \int_{a}^{b} [f(x)]^{2} \, dx \]
Substitute \( f(x) = \sin x \) and the limits \( a = 0 \), \( b = \pi \) into the volume formula: \[ V = \pi \int_{0}^{\pi} (\sin x)^{2} \, dx \]
Use the trigonometric identity to simplify \( (\sin x)^2 \): \[ \sin^{2} x = \frac{1 - \cos(2x)}{2} \] Rewrite the integral using this identity.
Set up the integral for evaluation: \[ V = \pi \int_{0}^{\pi} \frac{1 - \cos(2x)}{2} \, dx \] From here, you can integrate term-by-term to find the volume.

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Volume of Solids of Revolution

This concept involves finding the volume of a 3D solid formed by rotating a 2D curve around an axis. The volume is typically calculated using integral calculus, where the shape is sliced into thin disks or washers perpendicular to the axis of rotation.
추천 영상:
04:48
Finding Volume Using Disks

Disk Method

The disk method calculates volume by summing up the volumes of infinitesimally thin circular disks formed when a region is revolved around an axis. Each disk's volume is π(radius)^2 times the thickness, and integration over the interval gives the total volume.
추천 영상:
06:30
Disk Method Using y-Axis

Properties of the Sine Function

Understanding the sine function, especially one arch from 0 to π, is crucial. The function y = sin x is positive and continuous in this interval, which defines the shape of the region being revolved and sets the limits of integration for the volume calculation.
추천 영상:
가이드 코스
06:21
Properties of Functions