Creo Reverse Engineering (Restyle) > Creating Polynomial Surfaces in Restyle > To Create a Triangular Surface Using Three Curves
  
To Create a Triangular Surface Using Three Curves
1. Click Restyle > Polynomial Surface > Triangular.
2. Select three curves to create a triangular surface such that these curves form a closed boundary as follows:
Holding down the CTRL key, select two curves in the first direction of the surface. The intersection of the two curves is the pole of the triangular surface.
Select a curve in the second direction of the surface.
A surface bounded by these three curves is created.