Question

if all the diagonals are drawn from a vertex of an n-gon, then how many triangle are formed??​

Answer 1

Answer:

This can easily be proved by the congruence of alternate interior angles. From a given vertex of a polygon with n sides, (n-3) diagonals can be drawn. Every diagonal drawn from a single vertex of a polygon creates one triangle within the polygon, except for the last diagonal, which creates two triangles.