BELL RINGER

5 m

11 m

1.Area = ?

7ft.

P = 30 ft.

A = ?

2.

Area of a Triangle?

6m10m

11m

A

B CD

Area of Δ ABC?

Area of Δ ADC?

AREA

Brief review of finding the area of a triangle, rectangle, and

parallelogram

Area of a Rectangle

Read p.410, 411

Area is not a LENGTH, rather it is the number of SQUARE units worth of space that a shape takes up.

A of rectangle = base * heightJust like the bell ringer from today’s lesson.

Area of a Parallelogram

The formula does not change!A=B*H

20 yds.

7 yds.5 yds. A = 20 *5

= 100 yd2

Why do you suppose this is? (Paste the triangle on the other side…)

Area of a Triangle

A = Base * Height *1/2

Where does the ½ come from??See example.Don’t forget, the ALTITUDE is the HEIGHT

4 cm

3 cm

2 ft9 ft

What about a Trapezoid?

b1

b2

h

A = (b1 + b2) * h * 1/2

See example to understand why . . .

CLASSWORK

p.413, #1-9, p.418, #1-11

E.C., p. 420, #20, 27