Usually none but it's quite possible for it to have two.
Each trapezium has 4 sides so 3 of them have 12 sides.
720 degrees * * * * * The internal angles of any quadrilateral add to 360 degrees.
There are 3 different types: ordinary, isosceles and right which has 2 right angles
2
As many or as few as you want. You choose a length and a rhombus with sides of that length can be drawn.
Infinitely many.
One pair.
Usually none but it's quite possible for it to have two.
Each trapezium has 4 sides so 3 of them have 12 sides.
720 degrees * * * * * The internal angles of any quadrilateral add to 360 degrees.
A trapezium has two diagonals.A 4 sided quadrilateral trapezium has 2 diagonals.
There are 3 different types: ordinary, isosceles and right which has 2 right angles
2
There are infinitly many types. However some broad (and not necessaryly exclusive) classes of trapezia are Right trapezia (with at least 1 right angle) Isoceles trapeziea (the non parallel sides are equal in length) parallelograms (both pairs of sides are parallel)
The meaning of this question is not clear. A square is a two dimensional reqular quadrilateral - a flat shape with four sides of equal length. The lengths can have any value. As such a square does not have a base, so it is not clear how the base of a square can have any length.
You need at least four triangles, or at least three trapeziums. Or two triangles and one trapezium.