pyramid
A pyramid
This would be a triangular prism.
Two three-dimensional shapes that have at least one triangle as a face include a triangular prism and a pyramid. In a pyramid, the outer faces are triangles, and they come together at one point. A triangular prism is a type of prism with a triangular base.
It doesn't exist. The least number of sides for a 3-D shape only made of triangles is 4.
Both have at least one hexagonal face (base). Both have six faces that are topologically equivalent (either rectangles, or triangles).
You need at least four triangles, or at least three trapeziums. Or two triangles and one trapezium.
It is 8 triangles
All triangles need at least two acute angles
Two Isosceles triangles.__ ^/ / / |/ / / |V --
only right tringles or HL triangles have at least 1 right angle
equilateral triangles and isosceles ones
A dodecahedron is a generic term which describes a 3-dimensional shape with 12 polygonal shapes. There are approx 6.4 million topologically different convex dodecahedra plus concave ones. There are at least three of these in which all faces are triangles. At the other extreme, it can be an endecagon (11-gon) based pyramid with 11 triangles. So a face can be any polygon with 3 to 11 sides.