Respuesta :

Answer:

21 sides

Step-by-step explanation:

I don't know the right, but this is an alternative solution you can use also. Since a triangle's angles add up to 180, I kept multiplying 180. 180x7=1260. And 7x3=21 because a triangle has 3 angles

Answer:

9

Step-by-step explanation:

If the number of sides of the polygon is n, then

S=1260=(n−2)⋅180

Dividing both sides by 180, we obtain

7=n−2

which implies that n=9.

Therefore, this polygon has nine sides and is a nonagon.