1. Area of Parallelograms, Triangles, and circles
Objective: Students will be able to use formulas to find the area of parallelograms, triangles, and circles.

2. Information
Circle Formula: πr2

3. Find area of Parallelogram
10 yd.
6 in.
15 in.
9 yd.

4. Find area of Parallelogram
14 cm.
20 in.
11 cm.
5 in.
7 in.
4 ft.
5 ft.
9 in.

5. Area of Triangles
10m
5in
15m
12in

6. Area of Triangle
3ft 8m
10ft 5m
20cm
7ft
6ft
2cm

7. Information Radius: distance from center to point on circle.
Circle: all points same distance from center.
Center: fixed point middle of circle
Chord: line connects two points on a circle; NOT through the center.
Diameter: distance across circle passing through center
Central Angle: angle created by going through the center pt.
Radius: distance from center to point on circle.
½ diameter
Circumference: distance around circle
Formula of circumference:
C = πd

8. Identify the circle parts

9. Find the area of a circle A=πr2
24ft.

10. Find the area of a circle
56cm.

11. Word Problem
I have a circular garden that has a diameter of 20ft. In the middle, I want to put a cement patio down for a sitting area. I want the slab to measure 10ft x 12ft.
Determine the area of the entire garden?
2. Determine the area of the cement patio.
3. I want to plant flowers in the area not taken up by the patio. How much space to I have to plant the flowers?

12. Word Problem
I’m painting a room in my house. The room is made up of 4 walls all rectangular in shape. The walls are 12ft long and 9ft high. One wall has a window that is 4ft by 4ft. Another wall has a door 3ft by 7ft. I’m going to buy a gallon of paint that covers 50ft2. How many gallons do I need to buy if I want to do 2 coats of paint and what would the cost be if each gallon was $13 including tax?

13. Wrap-up
Question/Comments
Hw: worksheet