solid geogebra
facet normal 0.52 0.23 -0.81
    outer loop
        vertex 0.00 0.00 8.20
        vertex -2.57 -23.06 0.00
        vertex -18.68 13.76 0.00
    endloop
endfacet
facet normal 0.59 0.80 -0.00
    outer loop
        vertex -18.68 13.76 0.00
        vertex 0.00 0.00 32.81
        vertex 0.00 0.00 8.20
    endloop
endfacet
facet normal 0.99 -0.11 -0.00
    outer loop
        vertex -2.57 -23.06 0.00
        vertex 0.00 0.00 8.20
        vertex 0.00 0.00 32.81
    endloop
endfacet
facet normal -0.86 -0.37 0.33
    outer loop
        vertex -2.57 -23.06 0.00
        vertex 0.00 0.00 32.81
        vertex -18.68 13.76 0.00
    endloop
endfacet
endsolid geogebra