Sections Developing Algebraic Formulas: Perimeter of Regular Polygons Developing Algebraic Formulas: Perimeter of Regular Polygons (cont.) Developing Algebraic Formulas: Triangular Numbers Developing Algebraic Formulas: Perimeter of Regular Polygons Developing Algebraic Formulas: Perimeter of Regular Polygons (cont.) Developing Algebraic Formulas: Triangular Numbers Print Share Developing Algebraic Expressions to Represent Geometric Properties Copy and paste the link code above.