2. 1 Area of Triangles Press Ctrl-A ©2009 G Dear – Not to be sold/Free to use Web Resources Stage 4 Years 7 & 8

3. 2 Triangle Areas (1/8) The area of a triangle is half the area of the rectangle. Press h b base height Area = x rectangle 1212 Area = x b x h 1212 End of Slide

4. 3 Triangle Areas (2/8) Press h b base height Area = x rectangle 1212 Area = x b x h 1212 1212 1212 The area of a triangle is half the area of the rectangle. End of Slide

5. 4 Triangle Areas (3/8) The area of a triangle is half the area of the rectangle. h b base Area = x (a + b) h 1212 - x a x h 1212 a height = ah 1212 + bh 1212 - ah 1212 = bh 1212 Mathmatica End of Slide

6. 5 Triangle Areas (4/8) h h h b b b Area = x base x height 1212 A = bh 1212 End of Slide

7. 6 Triangle Areas (5/8) 8cm 5cm A B C D 10 20 30 40 X  End of Slide

8. 7 Triangle Areas (6/8) 6cm 4cm A B C D 46 18 24 12 X  End of Slide

9. 8 Triangle Areas (7/8) 20cm 7cm A B C D 10 20 70 40 X  End of Slide

10. 9 13.3 – Composite Areas (8/8) Compound Areas (Add) A Triangle = 0.5 x b x h 4 m = 0.5 x 6 x 3 = 9 m 2 6 m 3 m Press A Rectangle = L x B = 6 x 4 = 24 m 2 A Total = A Triangle + A Rectangle = 9 + 24 = 33 m 2 End of Show