Two triangles
You can divide a quadrilateral up into as many triangles as you want, but at least two.
No. Quadrilateral means "four sides." Triangles have three sides.
2
Infinitely many. Any triangle inside a quadrilateral can be divided into two without affecting the quadrilateral but increasing the number of triangles by 1. And then one of those triangles could be spilt into two and so on - without end.
If the triangles are congruent and you match the hypotenera the right way, you can get a rectangle. If the triangles are not congruent, you can't even necessarily get a quadrilateral.
You can put 2 triangles in a square or you can call it a quadrilateral.
8
Two scalene right triangles that are congruent, that is, that have identical size and shape, if joined together to form a quadrilateral, will form a rectangle.
The most right angles a triangle can possibly have is 1. Any more than that, and it has to be a quadrilateral.
it's impossible to have a quadrilateral that can't be cut into triangles.
4