• A quadrilateral has four sides, four angles and four vertices.
• The sum of all the angles of a quadrilateral is 360°.
• Parallelogram - A quadrilateralthat has both pairs of opposite sides parallel. It is a trapezium.
• Rectangle – A parallelogramthat has one of its angles a right angle.
• Rhombus - A parallelogram that has all its sides equal.
• Square - A parallelogram that has one of its angles a right angle and all sides equal. It is a rectangle and also a rhombus.
• Trapezium - One pair of opposite sides of quadrilateral are parallel. It is not a parallelogramas only one pair of opposite sides is parallel.
• Kite - A quadrilateral that has two pairs of adjacent sides equal. It is not a parallelogram.
• A rectangle or a rhombus is not a square.
• In a parallelogram:
• diagonal divides it into two congruent triangles
• opposite sides are equal
• pair of opposite sides is equal and parallel
• opposite angles are equal
• each pair of opposite angles is equal
• diagonals bisect each other
• Diagonals of a rectangle bisect each other and are equal.
• Diagonals of a rhombus bisect each other at right angles.
• Diagonals of a square bisect each other at right angles and are equal.
• The line-segment joining the mid-points of any two sides of a triangle is parallel to the third side and is half of it.
• A line through the mid-point of a side of a triangle parallel to another side bisects the third side.
• The quadrilateral formed by joining the mid-points of the sides of a quadrilateral, taken in order, is a parallelogram.

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