(n-2)*180
3420 degrees
Chat with our AI personalities
a decadogon
Icosihenagon
Each interior angle measures 162.'857142' degrees recurring '857142'
The number of triangles formed by the diagonals of a 21 sided polygon is C(21,3) = 21x20x19/3x2x1 = 1,330.
Let the measure of the first angle be x⁰. So that the second angle would be (x + 21)⁰, and the third one would be (x - 15)⁰.Since the sum of angle measures in a triangle is 180⁰ we have:x + x + 21 + x - 15 = 1803x = 174x = 58Thus, the first angle is 58⁰, the second angle is 79⁰, and the third angle is 43⁰.