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.
Depending on their shapes and sizes you can make plane shapes with 3 to 24 sides.
use 4 triangles, make 2 trapezoids then put them into a hexagon
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.