Triple integral forming a solid region

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nysnacc
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Homework Statement


Printed exercise showing the triple iterated integral from 0 to 1 in y, from y to 1 in z, and from 0 to z in x of F(x, y, z) dx dz dy, with instructions to sketch the region and count faces, corners and edges.


Homework Equations


Fubini's theorum

The Attempt at a Solution


I drawn the diagram with the limits (for x, y, and z)
and come up with something with 4 faces, 5 corners, 8 edges

is that something you guys got? Thanks
 
I also come up with a different number of faces
 
BvU said:
I also come up with a different number of faces
Like how many as what am I doing wrong??

Hand-drawn 3D sketch of a solid region on x, y and z axes, with the corner point (0, 1, y) labelled, outlined in blue, with a green outline of a base in the xy-plane.
The x limit is 0 and z, so for z, it is between y and 1, so I put 1 as upper limit for x.
 
nysnacc said:
Like how many as what am I doing wrong??The x limit is 0 and z, so for z, it is between y and 1, so I put 1 as upper limit for x.
One of the faces is part of the plane ##x=z##. You don't have that in your picture.
 
I count five faces on your drawings too...
z = 1 is one plane, a square face
x = 0 is a triangular face
y = 0 is a triangular face, not a square face: x runs from 0 to z, not from 0 to 1.
the other two triangular faces have x=y=z as edge in common
 
so it's like a square on top with the edges pointering to a single point on bottom?
 
nysnacc said:
so it's like a square on top with the edges pointering to a single point on bottom?
That's right - like the Great Pyramid (disregarding the references to 'top' and 'bottom'). This shape is known as a 'square pyramid'. The word 'square' is included to distinguish it from a tetrahedron or triangular pyramid. But in common language, the word 'pyramid' usually implies a square base.
 
nysnacc said:
so it's like a square on top with the edges pointering to a single point on bottom?

Now that you have it, here's a nice picture:
3D coordinate diagram with labeled X, Y and Z axes showing a solid region bounded by a light blue triangular face, a light pink face and a green triangular face, with dashed projection lines to the base.

Now the trick for you is to set up the six integrals. Do you see why when you do ##dz## first something is a bit more complicated?
 
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