5-Minute Check on Lesson 11-15-Minute Check on Lesson 11-15-Minute Check on Lesson 11-15-Minute Check on Lesson 11-1 Transparency 11-2

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Find the area and the perimeter of each parallelogram. Round to the nearest tenth if necessary.

1. 2.

3. 4.

TRY: Find the height and base of this parallelogram if the area is 168 square units

11 cm

13 cm

45°

60°

11 in

18 in

x + 2

x

6.3 m

17 ft

12 ft

Lesson 11-2 Day 1

Areas of Triangles

Area of Triangles

Triangle AreaA = ½ * b * h h is height (altitude)b is base (┴ to h)

R

S TW

h

EXAMPLE 1R

S TW

h

Find the area of triangle RST

10 10

45°

Find the area of quadrilateral ABCD if AC = 35, BF = 18, and DE = 10.

EXAMPLE 2

Find the area of quadrilateral HIJK if IK = 16, HL = 5 and JM = 9

EXAMPLE 3

EXAMPLE 4

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

EXAMPLE 5

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

Summary & Homework

Summary: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!!!