The document discusses the sum of interior angles for triangles, quadrilaterals, and pentagons. It shows that the sum of angles in a triangle is 180 degrees, a quadrilateral is 360 degrees (split into two 180 degree triangles), and a pentagon is 540 degrees (split into three 180 degree triangles). It then generalizes that the sum of interior angles of any n-sided polygon is (n-2) * 180 degrees.

3. Number of sides, n=3
Sum of angles of a triangle is 180◦
ie. ,sum of angles =(3-2)180◦

4. Now the quadrilateral is split into two triangles.
Number of sides, n=4
SUM OF ANGLES OF A QUADRILATERAL =180◦+180◦
=2*180◦
=360◦
ie. , sum of angles =(4-2)180◦

5. A pentagon is split into three triangles.
Number of sides, n=5
SUM OF ANGLES OF A PENTAGON =180◦+180◦+180◦
=3*180◦
=540◦
i e.,sum of angles =(5-2)180◦

6. THE SUM OF THE INTERIOR
ANGLES OF AN n-SIDED
POLYGON IS (n-2)180◦.