How Do You Find the Minimal Volume of a Tetrahedron Passing Through a Point?

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SUMMARY

The discussion focuses on finding the minimal volume of a tetrahedron defined by a plane that intersects the coordinate axes and passes through a specific point P(x0, y0, z0). The volume of the tetrahedron is derived from the equation of the plane, given by x/a + y/b + z/c = 1, where (a, 0, 0), (0, b, 0), and (0, 0, c) are the intercepts on the axes. To minimize the volume, the constraint x0/a + y0/b + z0/c = 1 must be satisfied. The participants clarify the derivation of the volume formula and the necessary conditions for the tetrahedron's vertices.

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i have the point P(x0,y0,z0) i need to find the minimal volume of a tetrahedron which is constructed by a plane which crosses over point P, and by the axis planes.

i got that the side of the tetrahedron is sqrt[(x-x0)^2+(y-y0)^2+(z-z0)^2], but I am not sure it's correct because then the answer is that the volume of the tetrahedron is 0.

your help is appreciated.
 
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The plane that crosses the axes at (a, 0, 0), (0, b, 0), and (0, 0, c) has equation x/a+ y/b+ z/c= 1 (do you see why that's obvious?). What is the volume of that tetrahedron? Of course, to pass through the point (x0,y0,z0), it must also satisfy
x0/a+ y0/b+ z0/c= 1.

So, minimize that formula for volume of a tetrahedron (in terms of a, b, c) subject to that constraint.
 
HallsofIvy said:
The plane that crosses the axes at (a, 0, 0), (0, b, 0), and (0, 0, c) has equation x/a+ y/b+ z/c= 1 (do you see why that's obvious?). What is the volume of that tetrahedron? Of course, to pass through the point (x0,y0,z0), it must also satisfy
x0/a+ y0/b+ z0/c= 1.

So, minimize that formula for volume of a tetrahedron (in terms of a, b, c) subject to that constraint.
can you tell me how did you arrive at the equation?
cause from what i can remember, you start by constructing vectors from the three points:
(a,0,-c),(a,-b,0),(0,-b,c) and then you substract them and you get the next parameter equation:
(0,-b,c)+s(-a,0,c)+t(-a,-b,2c)
and then multiply by coeffiecient vector (A,B,C), and then plug in (0,-b,c)
which i get the next equation:
x/a+y/b+z/c=0 without the 1, where did i get it wrong?
 

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