When a rectangular polygon with n sides is decomposed into triangles using the same vertex how many triangles are formed
To decompose a rectangular polygon with n sides into triangles using the same vertex, we can draw n-2 diagonal lines from one vertex to the other vertices (excluding the adjacent ones). Each diagonal line will form a triangle.
Therefore, when a rectangular polygon with n sides is decomposed into triangles using the same vertex, the number of triangles formed is n-2.