1. Lesson 8.4 Area of Triangles Pages 430 - 433

2. How do you find the area of a triangle? Draw a triangle on the grid paper. Enclose the triangle in a rectangle. Compare the area of the rectangle to the area of the triangle.

3. To find the area of a triangle, you need to know the length of the base and the height. The height of a triangle is the perpendicular segment from a vertex to a line containing the opposite side. The opposite side is called the base of the triangle. base height base height Area of a Triangle = ½ (base)(height) = ½ b h

4. Find the area. 10 cm 6 cm 5 ft 8 ft 16 cm 15 cm

5. Find the missing length (work backwards). Area = 84 in 2 14 in x Area = 39 yd 2 13 inches x x

6. Area of Similar Polygons If two polygons are similar with a scale factor of a:b, then the ratio of their areas is a 2 :b 2. 2 4 3 A D F E C B 6

7. Assignment: Pages 434 - 437 #5-13 all, #16-27 all, #32-35all