That did the trick, thanks!!
// Draw a right triangle in the upper left corner of an MFD
oapi::IVECTOR2 pt1, pt2, pt3;
pt1.x = 2; pt1.y = 2;
pt2.x = 65; pt2.y = 65;
pt3.x = 2; pt3.y = 65;
oapi::IVECTOR2 ptarr[3] = {pt1,pt2,pt3};
skp->Polygon(ptarr, 3);