There are infinitely many possible answers. One of these is a icosahedron.
Because it hasn't any straight lines that meet each other at an angle and it's circular in shape
A square and rectangle both have congruent triangles in them.
A football is circular, or rather spherical, because no other shape will roll in any direction.
the shape that can make two smaller triangles is parallelogram.
The answer depends on the shape. There are different formulae for triangles, quadrilaterals and other polygons. Since you have not bothered to provide any information on the shape,I cannot provide a more useful answer.The answer depends on the shape. There are different formulae for triangles, quadrilaterals and other polygons. Since you have not bothered to provide any information on the shape,I cannot provide a more useful answer.The answer depends on the shape. There are different formulae for triangles, quadrilaterals and other polygons. Since you have not bothered to provide any information on the shape,I cannot provide a more useful answer.The answer depends on the shape. There are different formulae for triangles, quadrilaterals and other polygons. Since you have not bothered to provide any information on the shape,I cannot provide a more useful answer.
the bottom one is a square and the other 4 are triangles
congruent triangles
The simplest such shape is PYRAMID.
There can be no closed 3D shape with only one square and 3 triangles.
A nine sided shape has 7 triangles
There are 9 triangles in an 11 sided shape
Similar triangles