Plane Figures

SOL5.13GESMrs. 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.

Triangle(3 sides)

Hexagon(6 sides)

Pentagon(5 sides)

Quadrilateral(4 sides)

vertex

side

Octagon(8 sides)

4

4

4

3

3

3 3

3

3

3

3

22

2

22 2

2

2

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

QuadrilateralsTrapezoidExactly 1 pairof parallelsides

Parallelogram2 pairs of parallelsides

RhombusAll sides congruent

RectangleRight angles

SquareKite2 pairs of adjacent

congruent sides1 pair of congruent angles

QuadrilateralsTrapezoidExactly 1 pairof parallelsides

Parallelogram2 pairs of parallelsides

RhombusAll sides congruent

RectangleRight angles

SquareKite2 pairs of adjacent

congruent sides1 pair of congruent angles

Describe and Compare Polygons:

Sort polygons by their properties athttp://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

http://illuminations.nctm.org/ActivityDetail.aspx?ID=9

The angles of a triangle add to….

The angles of a quadrilateral add to….

Now explore further with this NCTM game:

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

Triangle(3 sides)

Octagon(8 sides)

Hexagon(6 sides)

Pentagon(5 sides)

Quadrilateral(4 sides)

These are regular polygons

4

4

4 5

5

5

5 2

2

2

2

2

2

2

2

3

3

3

3

3

Polygon Videos

BrainPop

Classifying Angles(Review)

Acute AngleAn 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 AngleAn obtuse angle has a measure between 90° and 180°.(obtuse = obese)

Straight AngleA 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.

6

4

4 4

4

Classifying Triangles

•Scalene triangle• No sides are the same (equal) length.

9

7

2

9

72

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

legs legs

hypotenuse 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.

RectangleRectangles

& 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.

SquareA square is a special rectangle. It is also a special rhombus.

Classifying Quadrilaterals

•Trapezoid• A quadrilateral with only one pair of

parallel sides.

Trapezoid

A

D

C

B

side A ll side C

side B ll side D

Quadrilateral Videos

ixl Classify Quadrilaterals

You now know all about Plane Figures!