A non-convex quadrilateral ABCD tiles the plane. What is a possible configuration of the angles at the vertices?
I: two types of vertices: 2 As and 2 Cs; 2 Bs and 2 Ds
II: one type of vertex: A, B, C, D
A) I only
B) II only
C) both I and II
D) neither I nor II

Question

A non-convex quadrilateral ABCD tiles the plane. What is a possible configuration of the angles at the vertices? 
I: two types of vertices: 2 As and 2 Cs; 2 Bs and 2 Ds
II: one type of vertex: A, B, C, D
A) I only
B) II only
C) both I and II
D) neither I nor II

Quizplus · Accepted Answer

The Answer of A non-convex quadrilateral ABCD tiles the plane. What is a possible configuration of the angles at the vertices? 
I: two types of vertices: 2 As and 2 Cs; 2 Bs and 2 Ds
II: one type of vertex: A, B, C, D
A) I only
B) II only
C) both I and II
D) neither I nor II

A Non-Convex Quadrilateral ABCD Tiles the Plane