?Graphics

?Polygon

Show[
      Graphics[ 
{RGBColor[0.2, 0.5, 0.3], 
          Polygon[ { {0, 0},  {1, 2}, {1, 
                5}}]}, 
PlotRange -> {{0, 10}, {0, 
              15}},     
AspectRatio -> 
          1.5,       
ImageSize -> {10, 
              15} 10    
]]

Show[
      Graphics3D[{
Polygon[{
{0, 0, 
                0}, {1, 1, 2}, {1, 2, 10}
}]}]]