Triangles Triply in Perspective

The following way of viewing triangles triply in perspective is of interest. Two triangles ABC and PQR are said to be “in perspective” if the joins of corresponding vertices be concurrent . Thus if U be the point of concurrency we have the following collineations:— 2. Triangles doubly in perspective are also triply in perspective. Let the two triangles ABC and PQR be doubly in perspective, the two centres of perspective being U and V.