It means the base in a 3D figure. For example, if it was a pyramid. the bottom part would be the base and you get the area of that base
A triangular base pyramid would fit the description.
Sometimes. Any face can be defined as a base of a prism; but pyramids may have one face that is a base and not a triangle.
Sometimes because a sphere which is a 3d figure has a diameter
It isn't clear how you would define the "perimeter" for a 3D figure. The base is the product of length x width.
A pyramid.
It means the base in a 3D figure. For example, if it was a pyramid. the bottom part would be the base and you get the area of that base
polyhedron
A triangular base pyramid would fit the description.
Sometimes. Any face can be defined as a base of a prism; but pyramids may have one face that is a base and not a triangle.
To find the base of a figure, you first need to identify the shape of the figure. The base of a figure is typically the bottom or lower side that forms the foundation or support for the rest of the shape. For example, in a triangle, the base is usually the side on which the triangle stands. In a rectangular prism, the base is one of the two parallel and congruent rectangular faces.
A triangular pyramid. It has triangles on its 3 sides and a triangle on the bottom for a base.
A 3D shape with one base and three faces can only have triangular faces.
Sometimes because a sphere which is a 3d figure has a diameter
The cone IS a 3d figure.
It isn't clear how you would define the "perimeter" for a 3D figure. The base is the product of length x width.
It depends on the type of figure. If it is a 2D figure, then it is called area. If it is a 3D figure, then it is called volume.