triangular prism
Because the base of a cone is round, it is the only three dimensional figure with only one vertex.
A sphere. All other solids, including cubes, rectangular prisms, and cones all have at least one vertex.
When the vertex lies on the x-axis. For example x = y2, the vertex is at the origin, and the parabola is lying on its side.
The sum of the angles around a vertex point in a plane will always be 360o. Picture a bicycle wheel with all its spokes radiating out from the hub. Now pick two spokes to form a vertex. Find the angle of your vertex, and then subtract it from 360o. As there are 360o in a circle, and your figure (the vertex) is a slice of the circle, its angle plus all the rest of the arc about the vertex will sum to 360o. If you've discovered the angle of your vertex, you cannot help but find the sum of the rest of the angles (if there are more than one) around your vertex.
A dodecagon has 12 sides. Whether or not from one vertex, the number of sides remains the same. Each vertex is formed when 2 sides meet.
A cone, possibly.
Cone
A conic section.
Because the base of a cone is round, it is the only three dimensional figure with only one vertex.
a pyramid
Yes, the point on the cone is a vertex.Typical math textbooks define a cone as "A solid figure with one circular face and one vertex." So yes, there is one vertex.
CONE
Pyramid
A hexagonal pyramid.
A cone+++The original answer also had "Cube", which is obviously wrong!
It could be a pyramid shape
Pyramid, base