Quadrilaterals
A polygon is a flat surfaced shape.
A quadrilateral is a four-sided polygon.
A rectangle is a quadrilateral whose opposite sides
are equal and parallel.
AB = DC
AD=BC
AB DC
AD
BC
means
is parallel to
A
rectangle has two axes of line symmetry.
It has rotational symmetry of order 2 i.e.
turn symmetry
All
the angles of a rectangle are right angles.
The
diagonals of a rectangle are equal and bisect
each other.
(Bisect
means cuts in half)
AC = BD.
OA=OB=OC=OD
A
square is a special rectangle.
It is a rectangle with all its sides equal.
AB ll CD
AD ll BC
AB=BC=CD=DA
A square
has four axes of line symmetry.
It has rotational
symmetry of order 4 i.e. turn symmetry
The diagonals of a square
(i) bisect the angles of the square.
(ii) bisect each other at right angles.
(iii) bisect the corner angles.
A kite
is a quadrilateral with one axis of line symmetry.
It has no rotational
symmetry.
A kite
has two pairs of adjacent sides equal.
The
diagonals cross at right angles, but do not bisect each other.
A rhombus is a special
kite with two axes of symmetry.
It has rotational symmetry of order 2 i.e.
turn symmetry
The diagonals of a rhombus bisect each other at right angles.
The diagonals of a rhombus bisect the corner angles.
The opposite sides of a rhombus are
parallel.
All the sides are equal, and opposite angles
are equal.
· Parallelogram
A parallelogram is a
quadrilateral with no axis of line symmetry.
It has rotational symmetry of order 2 i.e.
turn symmetry
The opposite sides of a
parallelogram are equal and parallel.
The opposite angles of a
parallelogram are equal.
A trapezium has one pair of parallel sides.
It has no rotational
symmetry.
An ordinary trapezium has no axis of line symmetry
An
isosceles trapezium has one axis of line symmetry
