Two pairs of touching sides are the same length. The diagonals meet at right angles. Opposite sides are not parallel.
a square
A rectangle.
The answer depends on whether the shape is 2-dimensional or 3-d. For a 2-dimensional polygon with n sides, the minimum number is n-3 diagonals.
A triangle. Also, any shape that has no corners, such as a circle or an ellipse.
A Rectangle.
a square
a pentagon
A rectangle (or square), isosceles trapezium and some kites.
A rectangle has 2 pairs of parallel sides and its diagonals are of equal length but do not cross each other at 90 degrees
A rectangle.
The statements:It is a quadrilateral (a shape with 4 sides)It has two pairs of opposite sides equal of equal length which are parallelAll angles are equal at 90°The diagonals are equal in length and bisectall squares are rectangles but not all rectangles are squaresare all true about squares and rectangles
There are very many attributes. Some of these are:It is a two-dimensional shape. It has four sides. The sides are of equal length. It has two pairs of parallel sides. It has four vertices. Each vertex is a right angle. It has two diagonals. The diagonals bisect each other. The diagonals meet at right angles. It has rotational symmetry of order four. It has four axes of reflective symmetry. If the sides are of rational length then the diagonals are of irrational length (and conversely).
The answer depends on whether the shape is 2-dimensional or 3-d. For a 2-dimensional polygon with n sides, the minimum number is n-3 diagonals.
triangle
A square and a rectangle have diagonals of equal lengths
A triangle. Also, any shape that has no corners, such as a circle or an ellipse.
It is a two-dimensional (plane) shape bounded by four straight sides with equal length but which does not have an interior angle of 90 degrees. Other properties, like parallel sides, equal opposite angles, bisecting diagonals etc all follow from these.