Find Volume of Region: Tetrahedron Bounded by Coordinate Planes & Plane

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Discussion Overview

The discussion revolves around calculating the volume of a tetrahedron in the first octant, which is bounded by the coordinate planes and a plane defined by three points: (1, 0, 0), (0, 2, 0), and (0, 0, 3). Participants explore the appropriate method for determining the volume, including the need for correct limits of integration.

Discussion Character

  • Exploratory, Technical explanation, Homework-related

Main Points Raised

  • One participant initially proposes using a triple integral with fixed limits to calculate the volume, suggesting an answer of 6.
  • Another participant points out that the limits used correspond to a cuboid rather than a tetrahedron, questioning the validity of the initial approach.
  • A later reply acknowledges the need to derive the equations of the planes that define the tetrahedron, indicating a realization of the oversight in the initial calculation.
  • It is noted that using constants for limits of integration results in the volume of a rectangular solid, not the intended tetrahedron.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the correct method for calculating the volume, as there is a recognition of the need for proper limits of integration and plane equations, but no agreement on the resolution of the initial calculation.

Contextual Notes

Participants have not yet established the equations of the planes that bound the tetrahedron, which is crucial for determining the correct limits of integration. The discussion reflects uncertainty regarding the initial approach and the necessary corrections.

DWill
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Find the volume of this region: The tetrahedron in the first octant bounded by the coordinate planes and the plane passing through (1, 0, 0), (0, 2, 0), and (0, 0, 3).


Looking at this problem I thought it just involved solving a fairly simple triple integral:

||| dz dy dx

With these limits of integration:
0 <= x <= 1
0 <= y <= 2
0 <= z <= 3

I get the answer 6, but my textbook says the answer is 1. Is this a typo in the textbook or did I do something stupid?
 
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What are the equations of the planes which make up the tetrahedron? What you have done appears to be calculating the volume of a cuboid in the first octant of dimensions 1x2x3. That's not the shape of a tetrahedron.
 
Oh I see, I have to come up with the equations of the planes myself. that was stupid of me..thanks!
 
Using constants for limits of integration gives the volume of the rectangular solid 0 <= x <= 1, 0 <= y <= 2, 0 <= z <= 3.
 

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