Construct/make a tetrahedron, which is three-dimensional.
Sort of depends on how the two triangles are beforehand. One nice way to make four equilateral triangles from six matchsticks is to make a tetrahedron (a triangular pyramid).
No.
Rhombus
a larger equilateral triangle
To create five triangles from the four triangles formed by nine matchsticks, you can move two matchsticks from one of the triangles to create a new triangle. Specifically, remove one matchstick from the base of one triangle and one from the apex of an adjacent triangle, and reposition them to form an additional triangle that shares sides with the existing triangles. This reconfiguration will yield a total of five triangles.
Sort of depends on how the two triangles are beforehand. One nice way to make four equilateral triangles from six matchsticks is to make a tetrahedron (a triangular pyramid).
A parallelogram.
Join the 6 triangles like pizza slices
Equilateral triangles are also equiangular.
No.
Rhombus
draw a big triangle then make a line halfway through it
a larger equilateral triangle
No but they will make a hexagon
Make a triangle, each of whose sides is 2 matchsticks long. This uses six matchsticks. Join the middle points of the sides of this triangle to one another - using another three match sticks. You will then have four small triangles and one large one.
Four equilateral triangles make up another equilateral triangle.
Many different types, but mostly equilateral triangles.