square
Trusses are structural elements made up of a series of interconnected triangles. This design helps to distribute loads efficiently and increase stability in buildings and bridges.
An hexagon is made up out of 4 triangles
The Great Pyramids at Giza are, but the Meso-Americans were truncated.
27, but you will have to prove it.
Israel
An object made up of three rectangles and two triangles could be a house. The rectangles can represent the main structure and the door, while the triangles can represent the roof. This simple geometric composition is often used in basic architectural designs or children's drawings of houses.
An octagon is made up from six triangles each containing 180 degrees.
a geometric shape made up of 20 triangles. :)
geodesic
Assuming ALL 22 triangles are congruent, this would be a 22-gon, also known as an icositedigon
It would depend on the triangles, but assuming they were equilateral or isosceles, a trapezoid if alternated in a line.
rectangular pyramid