circle
4 rectangles / Correction: two triangles.
Trapezoid.
triangles
Three triangles.
You can make any triangle, quadrilateral or pentagon with three suitable triangles.
They are 4 triangles and one square. What they might make when assembled together depends on their sizes and on the shapes of the triangles.
use 4 triangles, make 2 trapezoids then put them into a hexagon
Depending on their shapes and sizes you can make plane shapes with 3 to 24 sides.
Four triangles, similar to the large one, but one third the size.
4 rectangles / Correction: two triangles.
A rectangle and 4 triangles.
You can make 6
Four equilateral triangles make up another equilateral triangle.
Trapezoid.
triangles
There are technically many shapes that could be put into the form of a triangle, but only triangles can make real triangles (without getting into more complicated shapes).
Three triangles.