There is no shape which has only three rectangle. And, if it has other faces, then there are many possibilities.
What do you think. Rectangles and many others i forgot Quad= shape with 4 sides
No, the sets and subsets can be any shape, but circles and rectangles are neater. Also, circles or rectangles will usually intersect in only one part whereas very wriggly shapes can have multiple intersections.
Because it is only true for rectangles, not any other shape.
Square No, in general they are six rectangles. Only in special cases would they be squares.
No, they are the only numbers that are NOT rectangular in shape. (I think you knew this and screwed up your question.) That is, all non-primes can be arranged into the form of a rectangle - e.g. 21 can be organized as a rectangle with dimensions of 3 x 7. But prime numbers cannot be organized as rectangles.
An L is two rectangles. Just make sure you only count the place where they intersect once.
No. Only some parallelograms are rectangles. But all rectangles are parallelograms.
No. Only some rectangles are - when they are squares.
Only if 2 sides are parallel with each other, and the other two sides are also parallel with each other. All squares are rectangles. All rectangles are parallelograms. All parallelograms are 4 sided. But not all 4-sided are parallelograms, not all parallelograms are rectangles, and not all rectangles are squares.
A 3-d shape with 6 equal faces is a cube. It has 6 squares as it's faces. A 3-d shape with 6 equal faces and only 2 squares is a rectangular prism. It has 2 squares and 4 other rectangles (squares are rectangles too) as it's faces.
All squares are rectangles also, but not all rectangles are squares, only equilateral rectangles are considered square.