triangle
Sides: 3
# of Triangles:1
Sum of interior angles: 180
quadrilateral
Sides: 4
# of Triangles: 2
Sum of interior angles: 360
Pentagon
Sides: 5
# of Triangles: 3
Sum of interior angles: 540
Hexagon
Sides: 6
# of Triangles: 4
Sum of interior angles: 720
Heptagon
Sides: 7
# of Triangles: 5
Sum of interior angles: 900
Octagon
Sides:8
# of Triangles: 6
Sum of interior angles: 1080
Nonagon
Sides: 9
# of Triangles: 7
Sum of interior angles: 1260
Decagon
Sides: 10
# of Triangles: 8
Sum of interior angles: 1440
sum of interior angles of a polygon
180(n-2)
Interior Angle of a regular polygon
n-2(180) / n
Sum of exterior angles of a polygon
360
exterior angle of a regular polygon
360/n
number of sides of a regular polygon
n