Question

I need an example of a concave polyhedron

Answer 1

Answer:

Examples of convex polygons:

In the adjoining figure of a parallelogram there are four interior angles i.e., ∠BAD, ∠ADC, ∠DCB and ∠CBA. None of the four interior angles is greater than equal to 180° and no portion of the diagonals lies in the exterior.

Convex Polygon Parallelogram