Skip to main content
Ch. 8 - Techniques of Integration
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077Non è quello che usi tu?Cambia libro di testo
Capitolo 8, Problema 8.2.61b

Finding volume: Find the volume of the solid generated by revolving the region in the first quadrant bounded by the coordinate axes and the curve y = cos(x), 0 ≤ x ≤ π/2, about
b. The line x = π/2.

Guida verificata passo dopo passo
1
Identify the region to be revolved: it is bounded by the x-axis (y=0), the y-axis (x=0), and the curve \(y = \cos(x)\) for \(0 \leq x \leq \frac{\pi}{2}\), all in the first quadrant.
Since the solid is generated by revolving the region about the vertical line \(x = \frac{\pi}{2}\), use the method of cylindrical shells to find the volume.
Set up the volume integral using cylindrical shells: the radius of a shell is the horizontal distance from \(x\) to the line \(x = \frac{\pi}{2}\), which is \(r = \frac{\pi}{2} - x\), and the height of the shell is \(h = \cos(x)\).
Write the volume integral as \(V = 2\pi \int_0^{\frac{\pi}{2}} (\text{radius})(\text{height}) \, dx = 2\pi \int_0^{\frac{\pi}{2}} \left( \frac{\pi}{2} - x \right) \cos(x) \, dx\).
Evaluate the integral by applying integration techniques such as integration by parts to find the volume.

Risposta video verificata per un problema simile:

Questa soluzione video è stata consigliata dai nostri tutor come utile per risolvere questo problema.
Durata del video:
6m

Concetti chiave

Ecco i concetti essenziali che devi comprendere per rispondere correttamente alla domanda.

Volume of Solids of Revolution

This concept involves finding the volume of a 3D solid formed by rotating a 2D region around a given axis. The volume can be computed using integral methods such as the disk, washer, or shell method, depending on the axis of rotation and the shape of the region.
Video consigliato:
04:48
Finding Volume Using Disks

Shell Method

The shell method calculates volume by integrating cylindrical shells formed by revolving vertical or horizontal slices around an axis. It is especially useful when the axis of rotation is vertical and not the y-axis, as in this problem where the region is revolved around x = π/2.
Video consigliato:
07:33
Euler's Method

Trigonometric Functions and Their Graphs

Understanding the behavior of y = cos(x) on the interval [0, π/2] is essential. The cosine function decreases from 1 to 0 in this range, defining the boundary of the region to be revolved. This knowledge helps set up correct limits and integrand expressions for volume calculation.
Video consigliato:
Percorso guidato
6:04
Introduction to Trigonometric Functions