# project 2d function into 3d

Say I have a simple 2D function like $y=100-x^2$. I want to also represent it in a third dimension "z". I will then combine this with a 3-dimensional figure (say Plot3D depiction of a pyramid) so that the vertical projection of $y=100-x^2$ "slices" the pyramid.

I've got this:

p41 = Plot3D[(1/2) ((1 - x/8) + (1 - y/17) -
Abs[(1 - x/8) - (1 - y/17)]), {y, 5, 17}, {x, 5, 8},
BoxRatios -> 1, FaceGrids -> All,
PlotStyle -> {Green, Opacity[0.2]}, ViewPoint -> {2, 2, 2},
PlotRange -> {{0, 17}, {0, 10}, {0, 1.5}}, ImageSize -> Large]

p42 = Plot3D[0 x + 0 y, {y, 0, 17}, {x, 0, 10}, PlotStyle -> Yellow]


I can combine them using Show[p41, p42]. I would also like to add in a vertical 3D surface in {x, y, z} space with something like:

p43 = Plot[10 - x^1.3/4, {x, 0, 17}] • $y = 100-x^2$ is not a 2D function. Find an online plot such as you seek and we'll show you how to program it. – David G. Stork Jul 19 '17 at 18:50
• I've got this: p41 = Plot3D[(1/2) ((1 - x/8) + (1 - y/17) - Abs[(1 - x/8) - (1 - y/17)]), {y, 5, 17}, {x, 5, 8}, BoxRatios -> 1, FaceGrids -> All, PlotStyle -> {Green, Opacity[0.2]}, ViewPoint -> {2, 2, 2}, PlotRange -> {{0, 17}, {0, 10}, {0, 1.5}}, ImageSize -> Large], this: p42 = Plot3D[0 x + 0 y, {y, 0, 17}, {x, 0, 10}, PlotStyle -> Yellow]. I can combine them using Show[p41, p42]. I would also like to add in a vertical 3D surface in {x, y, z} space with something like: p43 = Plot[10 - x^1.3/4, {x, 0, 17}]. – John Jul 19 '17 at 23:44

Show[