Extrude with the same angle

hello, a simple question but difficult for me,
Please see the file:)
I want to extrude (a solid) from a surface with the same angle that the pyramid (but without know the angle). How can I do please?

Thanks a lot,

nicolastest.3dm (2.7 MB)

there are 2 methods, one you explode the object and copy all the surfaces up with midpoint snaps turned on, then use create solid or trim at your height and use create solid.

or if you want it to extend to a point, you measure the angle with the command angle (be aware to measure first up then the angle in your case it is 23.079°), and use this as a reference for ExtrudeCrvTapered and use create solids again.

Bildschirmfoto 2021-03-08 um 15.46.51

One other way to do this - use Extrude (curve) straight on one upper edge with the Direction option, get the direction from one of the lower slanted faces…