3. Objectives
01
02
Recognize line symmetry and rotational
symmetry in 2D shapes, and identify different
properties of 2D shapes
identify and
describe the
hierarchy of
quadrilaterals.
4. Lines of
Symmetry
• A line that can be drawn through a shape so
that what can be see on either side is a mirror
image.
• It is sometimes called a Mirror Line
7. Some shapes have more than 2 lines of
symmetry
Square Equilateral Triangle Circle
8. Rectangle
2 lines of symmetry
Square
4 lines of symmetry
Rhombus
2 lines of symmetry
Equilateral Triangle
3 lines of symmetry
Isosceles triangle
1 line of symmetry
Isosceles Trapezium
1 line of symmetry
Kite
1 line of symmetry
Trapezium
No lines of symmetry
Parallelogram
no lines of symmetry
Regular Pentagon
5 lines of symmetry
Regular Hexagon
6 lines of symmetry
Regular Heptagon
7 lines of symmetry
The number of lines of symmetry in a regular polygon is equal to the number of sides.
14. These figures are not polygons These figures are polygons
Definition:A closed figure formed by a finite number of coplanar
segments so that each segment intersects exactly two
others, but only at their endpoints.
Polygons
15. Classifications of a Polygon
Regular: A polygon in which all angles are congruent and all sides
are congruent
That’s an equiangular equilateral polygon.
Irregular: A polygon that is not regular
18. What is a Quadrilateral?
• A quadrilateral is a
two-dimensional figure
with four sides and
four angles.
• The word part “quad”
means 4 and “lateral”
means sides.
21. A SQUARE
• A square is a
quadrilateral with 4
equal sides and 4 right
angles.
22. A RECTANGLE
• A rectangle is a
quadrilateral with 4
right angles.
• Its opposite sides are
equal and parallel.
23. Is a square a rectangle?
REMEMBER:
• A rectangle is a quadrilateral with 4 right angles.
Its opposite sides are equal and parallel.
• A square is a quadrilateral with 4 equal sides and 4
right angles.
Rectangle?
24. Is a rectangle a
square?
REMEMBER:
• A rectangle is a quadrilateral with 4 right angles. Its
opposite sides are equal and parallel.
• A square is a quadrilateral with 4 equal sides and 4
right angles.
Square?
25. Determination…..
• A square can also be called a
rectangle because it has four
right angles and its opposite
sides are equal and parallel.
A rectangle is NOT a square because it does
not have equal sides.
26. A TRAPEZOID
• A trapezoid is a
quadrilateral that has
exactly 1 pair of parallel
sides.
27. IS THIS A TRAPEZOID?
◦ Yes, it has one set of parallel sides.
28. A RHOMBUS • A rhombus is a quadrilateral that has 4 equal
sides. Its opposite sides are parallel.
29. A PARALLELOGRAM
• A parallelogram is a quadrilateral that
has opposite sides that are equal and
parallel.
• Which of the quadrilaterals we have
seen are parallelograms?
31. Have 4 sides and 4 angles
Has opposite sides that
are equal and parallel.
Has 1 pair of
parallel sides.
Has 4 right angles.
Opposite sides are
equal and parallel.
Has 4 equal sides.
Opposite sides
are parallel.
Has 4 equal sides and
4 right angles.
What conclusions can we draw from the
graphic?
32. A square can also be called a rhombus, a
rectangle, a parallelogram,
and a quadrilateral.
A rectangle can also be called a parallelogram
and a quadrilateral.
A rhombus can also be called a parallelogram
and a quadrilateral.
A parallelogram can also be called a
quadrilateral.
A trapezoid is a
quadrilateral.
Have 4 sides and 4 angles
Has opposite sides that
are equal and parallel.
Has 1 pair of
parallel sides.
Has 4 right angles.
Opposite sides are
equal and parallel.
Has 4 equal sides.
Opposite sides
are parallel.
Has 4 equal sides and
4 right angles.
33. Rectangle 2 pairs of sides of equal length
2 pairs of parallel sides
All angles 90°
Diagonals that bisect each other
2 lines of symmetry
Order 2 rotational symmetry
Square All sides have the same length
All angles 90°
2 pairs of parallel sides
Diagonals that bisect each other
at 90°
4 lines of symmetry
Order 4 rotational symmetry
•Properties of Quadrilaterals.
•A quadrilateral is an enclosed 4-sided flat shape.
•The angle sum of any quadrilateral is 360°.
Parallelogram 2 pairs of sides of equal length
2 pairs of parallel sides
Opposite angles are equal
Diagonals bisect each other
Sum of any two adjacent angles
is 180°
No lines of symmetry
Order 2 rotational symmetry
Rhombus All sides have the same length
2 pairs of parallel sides
Opposite angles are equal
Diagonals bisect each other
perpendicularly at 900
Sum of any two adjacent angles
is 180°
2 lines of symmetry
Order 2 rotational symmetry
34. •Properties of Quadrilaterals.
•A quadrilateral is an enclosed 4-sided flat shape.
•The angle sum of any quadrilateral is 360°.
Kite 2 pairs of equal sides
No parallel sides
1 pair of equal angles
1 diagonal that bisects the other
Diagonals cross at 90°
1 line of symmetry
Order 1 rotational symmetry
Trapezium Sides of different lengths
Only one pair of parallel sides
Angles of different sizes
No lines of symmetry
Order 1 rotational symmetry
Isosceles Trapezium
2 equal sides
Only one pair of parallel sides
2 pairs of equal angles
1 line of symmetry
Order 1 of rotational symmetry
41. A square is a special rectangle.
A rectangle is a special parallelogram.
A rhombus is a special parallelogram.
A square is a special rhombus.
Book page
177
42. Example: No she hasn’t.
She could be describing either a rectangle or
a square. She also needs to say that all the
sides have the same length.
Book page
177
43. False. AC is the same length as BD
True
False. Angle CAB is the same size as angle ABD
True
Book page
178
44. • one pair of sides the same length
• one pair of parallel sides
• two pairs of equal angles.
Book page
178
45. An isosceles trapezium is always a trapezium but a
trapezium is not always an isosceles trapezium.
A rhombus is a special kite.
A parallelogram is a special trapezium.
Book page 179
46. Example: No, he hasn’t.
He has said that the kite has two pairs of equal angles, but it
only has one pair of equal angles.
Book page 179