Plane
Figures
SOL5.13
GES
Mrs. Norman
Which Shapes Are Polygons? Why?
Polygons
Not Polygons
What is a Polygon?
• A polygon is a closed plane figure made up
of line segments.
• The names of common polygons tell how
many sides the polygon has.
vertex
3
side
4
4
4
Triangle
(3 sides)
3
Quadrilateral
(4 sides)
3
3
3
3
Pentagon
(5 sides)
3
3
Hexagon
(6 sides)
2
2
2
2
2
2
2
2
Octagon
(8 sides)
Plane Geometric Figures
A polygon is a closed plane figure with straight sides.
A regular polygon has congruent sides.
congruent
the same size and shape
Bees love Hexagons
Trapezoi
Quadrilaterals
d
Exactly 1 pair
of parallel
sides
Parallelogram
2 pairs of parallel
sides
Rhombus
All sides congruent
Square
Kite
2 pairs of adjacent
congruent sides
1 pair of congruent angles
Rectangle
Right angles
Trapezoi
Quadrilaterals
d
Exactly 1 pair
of parallel
sides
Parallelogram
2 pairs of parallel
sides
Rhombus
All sides congruent
Square
Kite
2 pairs of adjacent
congruent sides
1 pair of congruent angles
Rectangle
Right angles
Describe and Compare Polygons:
Sort polygons by their properties at
http://illuminations.nctm.org/ActivityDetail.aspx
?ID=34
Go to this site to make shapes with a virtual geoboard!
http://matti.usu.edu/nlvm/nav/frames_asid_129_g_3_t_3.
html
If you annotate over the desktop with ActiveInspire you can
measure their sides and angles!
Adding Angles of Polygons
The angles of a triangle add to….
The angles of a quadrilateral add to….
Now explore further with this NCTM
game:
http://illuminations.nctm.org/ActivityDetai
l.aspx?ID=9
What is a Regular Polygon?
• Clue: What do these polygons have in
common?
• A regular polygon has sides of equal length and
angles of equal measure
5
4
4
4
Triangle
(3 sides)
5
3
5
5
Quadrilateral
(4 sides)
3
These are regular polygons
3
2
2
2
3
3
Pentagon
(5 sides)
2
2
2
Hexagon
(6 sides)
2
2
Octagon
(8 sides)
Polygon Videos
BrainPop
CLASSIFYING
ANGLES
(REVIEW)
ACUTE ANGLE
An acute angle has a measure between
0° and 90°.
(a cute = little)
RIGHT ANGLE
A right angle has a measure of
90°.
(square = right = 90°)
OBTUSE ANGLE
An obtuse angle has a measure between
90° and 180°.
(obtuse = obese)
STRAIGHT ANGLE
A straight angle has a measure of 180°.
(straight = flat)
CLASSIFYING
TRIANGLES
(REVIEW)
Classifying Triangles
• Equilateral triangle
• All sides are the same (equal) length.
The sum total of every triangle = 180°
So, if all of the angles are the same…
3 ÷ 180° = 60°
Each of the three angles of an
equilateral triangle is 60°
Classifying Triangles
• Isosceles triangle
• At least two sides are the same (equal) length.
4
4
6
4
4
Classifying Triangles
• Scalene triangle
• No sides are the same (equal) length.
9
2
7
9
2
7
Classifying Triangles
• Right triangle
• One angle is a right (90°) angle.
• The sides have special names.
• The legs are the two sides that form a right triangle
• The third side is the hypotenuse
hypotenuse
legs
legs
hypotenuse
Classifying Triangles
• Acute triangle
• All three angles are acute angles.
Classifying Triangles
• Obtuse triangle
• One angle is an obtuse angle.
CLASSIFYING
QUADRILATERALS
Classifying Quadrilaterals
• How do you classify quadrilaterals?
• Quadrilaterals can be classified by their
• angles
• pairs of sides.
• Remember that a quadrilateral is any polygon
with 4 sides.
Classifying Quadrilaterals
• Types of quadrilaterals?
Parallelogram
Rectangle
Rhombus
Square
Trapezoid
Classifying Quadrilaterals
• Parallelogram
• A quadrilateral with both pairs of opposite
sides
• parallel
• equal in length.
Parallelogram
Rectangle
Rhombus
Square
Classifying Quadrilaterals
• Rectangle
• A parallelogram with four right (90°) angles.
Rectangle
Rectangles &
rhombuses are
special
parallelograms.
Square
Classifying Quadrilaterals
• Rhombus
• A parallelogram with all sides the same
length.
Rhombus
Rectangles &
rhombuses
are special
parallelograms.
Square
Classifying Quadrilaterals
• Square
• A rectangle with all sides the same length.
A square is a
special
rectangle. It is
also a special
rhombus.
Square
Classifying Quadrilaterals
• Trapezoid
• A quadrilateral with only one pair of parallel
sides.
A
side A ll side C
D
Trapezoid
C
B
side B ll side D
Quadrilateral Videos
ixl Classify Quadrilaterals
You now know all about
Plane Figures!