Graphics3D[{Polygon[{{0., 0., 1.7321}, {0., 1.633, -0.57735}, {-1.4142, -0.8165, -0.57735}}], Polygon[{{0., 0., 1.7321}, {0., 1.633, -0.57735}, {1.4142, -0.8165, -0.57735}}], Polygon[{{0., 1.633, -0.57735}, {-1.4142, -0.8165, -0.57735}, {1.4142, -0.8165, -0.57735}}], Polygon[{{-1.4142, -0.8165, -0.57735}, {0., 0., 1.7321}, {1.4142, -0.8165, -0.57735}}]}, {AmbientLight -> GrayLevel[0.15], Axes -> True, PlotRange -> {{-2., 2.}, {-2., 2.}, {-1., 2.}}, AxesLabel -> {"x", "y", "z"}, TextStyle -> {FontFamily -> "Times", FontSize -> 16.}}]