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Transparency 11-2
5-Minute Check on Lesson 11-1
Find the area and the perimeter of each parallelogram. Round to the nearest tenth if necessary. 2.
TRY: Find the height and base of this parallelogram if the area is 168 square units
11 cm
13 cm
45°
17 ft
12 ft
6.3 m
60°
11 in
18 in
x + 2 x
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2. Lesson Day 1
Areas of Triangles

3. Area of Triangles A = ½ * b * h h is height (altitude)
Triangle Area
A = ½ * b * h
h is height (altitude)
b is base (┴ to h) h S T W

4. EXAMPLE 1 R
Find the area of triangle RST h
45° S T 10 W 10

5. EXAMPLE 2
Find the area of quadrilateral ABCD if AC = 35, BF = 18, and DE = 10.
Example 2-1a

6. EXAMPLE 3
Find the area of quadrilateral HIJK if IK = 16, HL = 5 and JM = 9
Example 2-1b

7. EXAMPLE 4
Find the area of the triangle whose vertices are (3,6), (7,6) and (3,1).

8. EXAMPLE 5
Find the area of the parallelogram whose vertices are (0,0), (4,0), (5,5), and (1,5)

9. Summary & Homework Summary: Classwork: YOU MUST SHOW WORK!!!!!
The formula for the area of a triangle can be used to find the areas of many different figures
Congruent figures have equal areas
Classwork: YOU MUST SHOW WORK!!!!!
pg 605 (5,13, 14, 19, 20, 34, 35)
pg 599 (21-25 and page 605 #7) Plot points first then find the area of each!!!