Minimizing Volume in 3-Space: Plane Equation?

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In summary: I see, the equation of a plane passing through (1,1,1) and enclosing the least amount of volume in the first octant is y=x in 3-space.In summary, the conversation discusses finding the equation of a plane that passes through a given point and encloses the least amount of volume in the first octant. There is a debate about whether or not a specific plane, y=x in 3-space, would enclose zero volume. The conversation concludes by suggesting that solving the problem in two different ways would provide both a "clever solution" and the intended solution.
  • #1
cragar
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I once had a home work question that asked us to find the equation of a plane that went through the point (1,1,1) an enclosed the least amount of volume in the first octant . I know how to do it with derivatives and all that but what if the plane was on edge going from (1,1,1) to the origin . It would be like having a sheet of glass bisect the corner of the room but my teacher said that it had no top on it and it enclosed no volume , so what do you guys think ?
I think the equation of my plane would be y=x in 3-space .
 
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  • #2
I think your teacher is completely correct! There are, in fact, an infinite number of planes passing through both (0, 0, 0) and (1, 1, 1) (y= x is one of them but rotating that around the line x= t+ 1, y= t+ 1, z= t+ 1 gives another for every angle of rotation between 0 and [itex]2\pi[/itex]) but none of then "cut off" a bounded region of the first octant.
 
  • #3
why can't we say it cuts off zero volume .
 
  • #4
Depending on the detailed wording of the problem (and the chosen definition of the word 'enclose'), you probably could.

But the best would be to solve the problem both ways, i.e. also assume that you're supposed to find the plane that cuts off the minimal volume in that octant, while intersecting somewhere on all three axes.

Then you'd have your "clever solution" as well as what is probably the "intended solution".
 
  • #5
ya i was thinking it would work
 

FAQ: Minimizing Volume in 3-Space: Plane Equation?

What is the formula for the equation of a plane in 3-dimensional space?

The general equation for a plane in 3-dimensional space is Ax + By + Cz + D = 0, where A, B, and C are the coefficients of the x, y, and z variables, and D is a constant.

How do you determine the coefficients of a plane's equation?

The coefficients of a plane's equation can be determined by using the coordinates of 3 points on the plane. These points can be used to create 3 equations, which can then be solved simultaneously to find the values of A, B, and C.

What is the significance of minimizing volume in 3-space?

Minimizing volume in 3-space is important in many practical applications, such as minimizing material usage in construction or optimizing the design of a product to reduce its cost. It is also a fundamental concept in mathematics and geometry.

Can the volume of a plane in 3-space ever be negative?

No, the volume of a plane in 3-space can never be negative. It is considered to be 0 if the plane is infinitely thin, and any positive value if the plane has thickness.

What are some techniques for minimizing volume in 3-space?

There are several techniques for minimizing volume in 3-space, such as using calculus to find the minimum value of a function, using geometric principles to optimize shapes, and using linear algebra to find the planes that enclose the minimum volume.

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