If you draw a 9-gon and then draw from one vertex all the possible triangle to the other vertices you'll get 7 triangles. Multiply 7 times 180, the number of interior ange measure, and you'll get your answer. 1260
360 degrees
180
35
360
180
360 degrees
180
720
360
35
360
180
If it's a regular 9 sided polygon then each interior angle will measure 140 degrees.
The sum of the measures of the angles in a figure having 9 sides is 20 degrees each angle.
Sum= 2340 Degrees A+
1,080
supplementary