MMO 195 Moscow MO 1951 concentric circles and polygon, pyramid
Source:
August 7, 2019
pyramidconcentric circlestangentialgeometry3D geometrypolygon
Problem Statement
We have two concentric circles. A polygon is circumscribed around the smaller circle and is contained entirely inside the greater circle. Perpendiculars from the common center of the circles to the sides of the polygon are extended till they intersect the greater circle. Each of the points obtained is connected with the endpoints of the corresponding side of the polygon . When is the resulting star-shaped polygon the unfolding of a pyramid?