Answer:
tridecagon/triskaidecagon
Step-by-step explanation:
sum of interior angles= 180(n−2) degrees, n being the number is sides in the polygon.
sum of interior angles= 1980
180(n−2)=1980
divide by 180:
n−2=1980180=11
add 2:
n=11+2=13
If a polygon has 13 sides, it is called a tridecagon or a triskaidecagon.