A triangular prism
It is a 3D 5-sided figure. 3 of the sides are rectangles and it has 2 bases that are triangles (top and bottom base). It typically looks like a "tent" like one that you camp in.
a pentagon yea buddy
triangular prism
It is a 2D net that represents a 3D figure
A pyramid.
There can be no closed 3D shape with only one square and 3 triangles.
a pyramid
A triangular base pyramid would fit the description.
The simplest pattern is 2n+1, so the 16th figure will have 33 triangles. Of course, if you are creating new triangles and also keeping the old triangles, this would be different.
This would be a triangular prism.
A triangular prism
An octagonal pyramid has eight triangles on an octagonal base. An octahedron can also be made by putting a square pyramid on another inverted square pyramid. This shape has just eight triangles and no others.
A circle is not a 3D figure because it only has two dimensions. A sphere is a 3D "circle".
It is a 3D 5-sided figure. 3 of the sides are rectangles and it has 2 bases that are triangles (top and bottom base). It typically looks like a "tent" like one that you camp in.
Triangular prism
A net has two equilateral triangles and 3 rectangles. What solid figure might it make?