In ${\mathbb R}^3$, try three concentric solid solid cones with different heights and the same base radius, axis and vertex (which isthe vertex being the intersection of the three boundaries).
In ${\mathbb R}^3$, try three concentric solid cones with different heights and the same base radius and vertex (which is the intersection of the three boundaries).
In ${\mathbb R}^3$, try three solid cones with different heights and the same base radius, axis and vertex (the vertex being the intersection of the three boundaries).
In ${\mathbb R}^3$, try three concentric solid cones with different heights and the same base radius and vertex (which is the intersection of the three boundaries).
In ${\mathbb R}^3$, try three solid cones with the same vertex (which is the intersection of the three boundaries).
In ${\mathbb R}^3$, try three concentric solid cones with different heights and the same base radius and vertex (which is the intersection of the three boundaries).