Triangular based pyramid with no bottom. That is, if you meant 3-D shapes, presumably?
A cube.
They are alike because they are both 3-D shapes
There are different formulae for different shapes and these vary in complexity.
Icosahedron are 3-D solid shapes with 20 triangualr faces. They are used as dice is many games, such as Dungeons & Dragons.
3-d shapes are not made from 2-d shapes. 3-d shapes may have projections onto a plane that are 2-d.
There are infinitely many 3-D shapes so it is not possible to name them individually.
If you can make it just by cutting it out of a piece of paper, it's 2-d. If you can make it by carving a block of wood, it's 3-d. 2-d shapes have length and width, but not height. 3-d shapes have length, width, and height. Here's an example: a rectangle might be 2" long and 5" wide, but those are the only numbers you use, so it's a 2-d shape. A house is 60' long, 25' wide, and 10' tall, so it's 3-d.
3 dimensional shapes have breadth, width and depth whereas 2 dimensional shapes have only breadth and width
Polyhedrons
-hedra.
Triangular based pyramid with no bottom. That is, if you meant 3-D shapes, presumably?
circles and ovals In 3-D, spheres and oblate spheroids
No because isosceles triangles are 2 dimensional shapes.
There are infinitely many such shapes. There are infinitely many such shapes. There are infinitely many such shapes. There are infinitely many such shapes.
There are no triangular prisms in faces. Faces are 2-d shapes and these cannot contain 3-d shapes in them.
4D includes smell.