Geometry Section 1-6 1112

Section 1-6
Two-Dimensional Figures
Monday, September 22, 14

Essential Questions
• How do you identify and name polygons?
• How do you find perimeter, circumference,
and area of two-dimensional figures?

Vocabulary
1. Polygon:
2. Vertex of a Polygon:
3. Concave:
4. Convex:
5. n-gon:
6. Equilateral Polygon:

Vocabulary
1. Pol y g o n : A closed figure whose sides are all line
segments
2. Vertex of a Polygon:
3. Concave:
4. Convex:
5. n-gon:

Vocabulary
segments
2. Ver t e x o f a P o l y g o n : The point where two sides of
a polygon meet
3. Concave:
4. Convex:
5. n-gon:

Vocabulary
segments
a polygon meet
3. Concave: A polygon that has an indentation
4. Convex:
5. n-gon:

Vocabulary
segments
a polygon meet
4. Convex: A polygon that has no indentations
5. n-gon:

Vocabulary
segments
a polygon meet
5. n-gon: A polygon that has n sides

Vocabulary
segments
a polygon meet
5. n-gon: A polygon that has n sides
6. Equ i la t e r a l P o l y g o n : A polygon where all sides are
congruent

Vocabulary
7. Equiangular Polygon:
8. Regular Polygon:
9. Perimeter:
10. Circumference:
11. Area:

Vocabulary
7. Equ i a n g u l a r P o l y g o n : A polygon where all angles
are congruent
8. Regular Polygon:
9. Perimeter:
10. Circumference:
11. Area:

Vocabulary
are congruent
8. Reg u la r P o l y g o n : A polygon where all sides are
congruent and all angles are congruent
9. Perimeter:
10. Circumference:
11. Area:

Vocabulary
are congruent
9. Per i m e t e r : The sum of the lengths of the sides of
a polygon; The distance around a polygon
10. Circumference:
11. Area:

Vocabulary
are congruent
10. Circumference: The distance around a circle
11. Area:

Vocabulary
are congruent
C = 2π r = π d
11. Area:

Vocabulary
are congruent
C = 2π r = π d
11. Area: The space in square units a figure covers

Area Formulas
Where are some places that you find these formulas?

Example 1
Make four drawings (using a straight edge) so
that two of your drawings are polygons and
two are not. Label which is which.
Polygons Not Polygons

Polygon Names
3 sides: 4 sides: 5 sides:

Polygon Names
Triangle

Polygon Names
Triangle Quadrilateral

Polygon Names
Triangle Quadrilateral Pentagon

Polygon Names
Hexagon

Polygon Names
Hexagon Heptagon

Polygon Names
Hexagon Heptagon Octagon

Polygon Names

Polygon Names
Nonagon

Polygon Names
Nonagon Decagon

Polygon Names
Nonagon Decagon Dodecagon

Example 2
Draw a concave hexagon. Then draw a convex octagon.

Example 3
Draw a regular quadrilateral.

Example 4
Identify the figure based on the number of
sides. Is it concave or convex? Is it equilateral,
equiangular, or neither?

Example 4
Decagon

Example 4
Decagon
Equilateral, but not equiangular

Example 4
Decagon
Concave
Equilateral, but not equiangular

Example 5
Find the perimeter of a rectangle whose length
is 8.3 cm and width is 3.2 cm.

Example 5
8.3 cm

Example 5
8.3 cm
3.2 cm

Example 5
8.3 cm
3.2 cm
P = 2l + 2w

Example 5
8.3 cm
3.2 cm
P = 2l + 2w
= 2(8.3) + 2(3.2)

Example 5
8.3 cm
3.2 cm
P = 2l + 2w
= 2(8.3) + 2(3.2)
= 16.6 + 6.4

Example 5
8.3 cm
3.2 cm
P = 2l + 2w
= 2(8.3) + 2(3.2)
= 16.6 + 6.4
= 23

Example 5
8.3 cm
3.2 cm
P = 2l + 2w
= 2(8.3) + 2(3.2)
= 16.6 + 6.4
= 23 cm

Example 6
Find the circumference of a circle with a
diameter of 14 in.

Example 6
diameter of 14 in.
14 in.

Example 6
diameter of 14 in.
14 in. C = 2π r = π d

Example 6
diameter of 14 in.
14 in. C = 2π r = π d
C = π d

Example 6
diameter of 14 in.
14 in. C = 2π r = π d
C = π d
C = π (14)

Example 6
diameter of 14 in.
14 in. C = 2π r = π d
C = π d
C = π (14)
C ≈ 43.98 in.

Problem Set

Problem Set
p. 61 #1-27 odd, 44-47
“Nobody got anywhere in the world by simply being
content.” - Louis L’Amour

Geometry Section 1-6 1112

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