 Hello and welcome to the session. In this session we discussed the following question which says, find the sum of the interior angles of a polygon of 13 sides. Before moving on to the solution, let's see what is the sum of the interior angles of a convex polygon of n sides. This is equal to 2n minus 4 right angles. This is the key idea that we use for this question. Let's proceed with the solution now. We are given a polygon of 13 sides. So the number of sides of the polygon is equal to 13. That is, we have n is equal to 13. Now from the key idea we have that the sum of the interior angles of a convex polygon of n sides is equal to 2n minus 4 right angles. Thus we can say sum of the interior angles of a polygon of 13 sides is equal to 2 into 13. That is in place of n, we put 13 minus 4 right angles. Or you can say this is equal to 26 minus 4 into 90 degree since one right angle is equal to 90 degree. This is equal to 22 into 90 degrees which comes out to be equal to 1980 degrees. Thus sum of the interior angles of a polygon of 13 sides is 1980 degrees. So 1980 degrees is our final answer. This completes the session. Hope you have understood the solution of this question.