1. Lesson: 10 – 3 Areas of Polygons
Applied Geometry
Lesson: 10 – 3
Areas of Polygons
Objective:
Learn to estimate the areas of polygons.

2. Polygonal Regions
Any polygon and its interior

3. Postulate 10-1 Area Postulate
For any polygon and a given unit of measure, there is a unique number A called the measure of the area of the polygon.

4. Postulate
Congruent polygons have equal measures.

5. Composite figures
Polygons that contain other polygons.

6. Postulate 10 – 3 Area Addition
The area of a given polygon equals the sum of the areas of the nonoverlapping polygons that form the given polygon.

7. Find the area of the polygon
Find the area of the polygon. Each square represents 1 square centimeter.
How many whole squares? 5
How many partial squares? 4
A = 5(1) + 4(0.5)
A = 7 cm2

8. Find the area of the polygon. Each square represents 1 square inch.
A = 5 in2

9. Irregular figures
Figures that are not polygons and cannot be made from combinations of polygons.

10. 2 15 A = 2(1) + 15(0.5) A = 9.5(3350) A = 2+ 7.5 Approximately 9.5
If Lake Superior were drained, the resulting land area would be twice that of the Netherlands. Estimate the area of Lake Superior if each square represents 3350 square miles.
How many whole squares? 2
How many partial squares? 15
A = 2(1) + 15(0.5)
A = 9.5(3350)
A =
A = 31,825 square miles
Approximately 9.5

11. Estimate the area of the polygon. Each square unit represents 1 acre.
A = 28.5 square acres

12. Homework
Pg – 8 all, 10 – 30 E