It depends what shape the base is:
Triangle: One-half times base times height
Rectangle: Length times width
Parallelogram: Base times height
Circle: Pi times radius squared
Square: Side squared
Other figures' areas are made up of these.
Tetrahedron
pyramid
It could be a pyramid.
It is simply called a face.
Cone
Tetrahedron
Because the base of a cone is round, it is the only three dimensional figure with only one vertex.
pyramid
pyramid or cone
It could be a pyramid.
Cone
A hemisphere is one example.
It can be a triangular based pyramid
It is simply called a face.
The lateral area of a three-dimensional figure refers to the surface area of the sides of the figure, excluding the top and bottom faces. It is calculated by summing the areas of all the vertical faces of the solid. For example, the lateral area of a cylinder is found by multiplying the circumference of the base by the height, while for a prism, it involves calculating the perimeter of the base times the height. This measurement helps in understanding the amount of material needed to cover the sides of the shape.
Tetrahedron has three sides and a base all triangular.
A hexagonal pyramid.