1. copyright©amberpasillas2010

2. The area of a rectangle is equal to the base times the height. Also known as length times width. height base (h) (b) A = bh A = bh is the same as A = lw

3. copyright©amberpasillas2010 What is the formula for area of a parallelogram ? Use this information to find the area of a parallelogram A has the same area as a rectangle! h base = b height = h h b

4. copyright©amberpasillas2010 Given the formula for area of a rectangle, we are going to use that information to discover the formula for the area of a triangle. Watch carefully not to miss it!

5. Given a right triangle Make a similar triangle,

6. Given a right triangle Make a similar triangle, flip it and put both triangles next to each other What polygon is this? A Rectangle

7. copyright©amberpasillas2010 What is the formula for the area of a triangle ? We can use the formula for area of a rectangle to find the formula for area of a triangle. Two triangles make one rectangle. We want to find half of the area of the rectangle. base height b h

8. When we put 2 right triangles together is made a rectangle. Watch what happens when instead we use 2 isosceles triangles.

9. Given an isosceles triangle Make a similar triangle,

10. Given an isosceles triangle Make a similar triangle, flip it and put both triangles next to each other What polygon is this? A Parallelogram

11. copyright©amberpasillas2010 base height h How do you find the area of the parallelogram?

12. copyright©amberpasillas2010 9 cm 5 cm6 cm 3 cm

13. # 4 Area of a Triangle 8 m 6 m A = 8 x 6 2 = 24 m 2 A = base x height 2 A triangle is half the area of a rectangle. To find the area of a triangle you use the rectangle formula and divide it in half.

14. copyright©amberpasillas2010 The End!