1. MJ3 Ch 7.1 – Area of Parallelograms, Triangles & Trapezoids

2. Bellwork Get your bellwork sheet and a pencil and meet me in front of the media center.

3. After The Activity Raise you hand if you can predict why I had you do this activity… What is perimeter? What is Area? From a rectangle we can create a parallelogram…(demonstrate w/index card) My comments….

4. Assignment Review None

5. Before we begin… Please take out your notebook and get ready to work… In the bellwork activity we looked at the perimeter of a square… At this stage you should all know the difference between perimeter and area… More specifically, you should know by rote memory how to calculate the area of a square or rectangle… In today’s lesson we will look at how to calculate the area of parallelograms, triangles and trapezoids…

6. Objective 7.1 Students will calculate the area of parallelograms, triangles and trapezoids using the formula method

7. The Formula Method First and foremost…in this chapter the only way that I will accept any answers is if you use the formula method! At this level you are required to demonstrate what you know and the formula method helps you do that. The formula method is:  Write the formula  Substitute  Do the math Note: Each time you perform a function you must rewrite the whole equation all over again…this strategy minimizes errors!

8. Example Calculate Area: 4 ft 8 ft 1. Write the Formula 2. Substitute 3. Do the math A = l ● w A = 4 ● 8 A = 32 ft 2 Note: The answer is squared because you are measuring 2 dimensions (Length & Width)

9. Parallograms Let’s look at the specific characteristics of a parallelogram… In a parallelogram the base can be any side. The height (altitude) is a line segment that is perpendicular to the base and runs to the opposite side. The formula for area of a parallelogram is: A = bh The formula can be found on the FCAT reference sheet

10. Example Find Area 12 m 5.25 m A = bh A = 5.25(12) A = 63 m 2 1. Write the Formula 2. Substitute 3. Do the math

11. Your Turn In the notes section of your notebook draw and label the picture and then calculate area using the formula method. 5 mm 25 mm 8 ft 16.25 ft

12. Triangles A diagonal drawn in a Parallograms will separate the parallelogram into 2 congruent triangles Therefore, the area of a triangle will be ½ of the area of a parallelogram The base can be any side and the height (altitude) is the line segment from the base to the opposite side. The formula for area of a triangle is A = ½ bh You can find this formula on the FCAT reference sheet Height Base

13. Example Calculate Area 4.5 m 8.5 m A = ½ bh A = ½ (8.5)(4.5) A = ½ (38.25) A = 19.125 m 2 1. Write the Formula 2. Substitute 3. Do the math

14. Your Turn In the notes section of your notebook draw and label the figure and then calculate area using the formula method 6 ft 10 m 10.5 ft 12 m 18 m 20 m

15. Trapezoids In chapter 6 we discussed trapezoids, which are quadrilaterals with 2 parallel sides. The parallel sides are the bases. It doesn’t matter which one you call b 1 or b 2 The formula for area of trapezoids is A = ½ h(b 1 + b 2 ) This formula can also be found on the FCAT reference sheet Parallel Sides

16. Example Calculate Area 6.5 mm 18.5 mm 9 mm 4.5 mm A = ½ h(b 1 + b 2 ) A = ½ (6.5)(18.5 + 9) A = ½ (6.5)(27.5) A = ½ (178.75) A = 89.375 mm 2 1. Write the Formula 2. Substitute 3. Do the math

17. Your Turn In the notes section of your notebook draw and label the figure and then calculate area using the formula method. 3.2 cm 6.5 cm 9 cm 4 cm

18. Summary In the notes section of your notebook summarize the key concepts covered in today’s lesson Today we discussed  The difference between perimeter & area  How to calculate area using the formula method

19. Assignment Text p. 317 # 7 – 15 You do not have to draw the figure. However, you must use the formula method to show how you got your answer. (no work = no credit) This assignment is due tomorrow I do not accept late assignments