I can’t see the picture so if you just want to comment and put it there I can help :)
Answer:
20 sides.
Step-by-step explanation:
The exterior angle = 180 - 162 = 18 degrees.
Since the sum of the exterior angles = 360 degrees the number of sides
= 360 / 18
= 20 sides.
Hmmm I'd say the center of the circle will end up at the center of the triangle, namely the
Centroid of the triangle circumscribed in the circle.