RENSSELAER – Developers have discovered what city officials call the "Rensselaer Triangle" with their multi-million dollar investments to build 210 apartment units over the last year has increased the city's housing units by 4.5 percent."Rensselaer is in the center of a development triangle – Regeneron, the State Capital and the Rensselaer Tech Park," said Charles Moore, the city's director of planning and development.