2. AREAS AND PERIMETERS TRIANGLE SQUARE RECTANGLE RHOMBUS TRAPEZIUM CIRCLE

3. TRIANGLE area perimeter Base times height over two Add the three sides up

4. height h h base bb area = 3cm 4cm 3cm 2cm E X A M P L E

5. b a c Perimeter = a + b + c EXAMPLE 5cm 3cm 4cm 3 + 5 + 4 = 12cm

6. area perimeter Side times side =side squared Addition of the sides SQUARE

7. Area = l l It must be the same shape as the rectangle Área = a·b a b 5cm E X A M P L E

8. Perimeter = l + l + l + l = 4·l l l 3cm 4·3 = 12cm EXAMPLE

9. area perimeter The longest side times the shortest side Addition of the sides Press here to see the development of the area formula Press here to see the development of the perimeter formula RECTANGLE

10. Area = a · b b a If the sides were equal, it would be useful for the square Area = a·b a b 3cm 5cm E X A M P L E

11. Perimeter = a + b + a + b = 2·a + 2·b = 2·(a+b) b a 3cm 5cm 2·(5+3) = 16cm E XA M P L E

12. area perimeter The longest diagonal times the shortest diagonal divided by two Addition of the sides Press here to see the development of the area formula Press here to see the development of the perimeter formula RHOMBUS

13. Example Area = D d 8cm 5cm

14. E XAMPLE Perimeter = l + l + l + l = 4·l 4·3 = 12cm l l 3cm

15. area perimeter Semiaddition of the bases times the height Addition of the sides Press here to see the development of the area formula Press here to see the development of the perimeter formula TRAPEZIUM

16. E X A M P L E If the bases were equal, we would have a rectangle. Area = a·b a b h height b1b1 b2b2 bases 5cm 3cm 2cm Area =

17. EXAMPLE Perimeter = b 1 + c + b 2 + a 7+3+5+4 = 19cm a b2b2 b1b1 c 4cm 5cm 7cm 3cm

18. circle circumference  times the radium squared  (pai)(3.14159...) Press here to see the developmet of the area formula Press here to see the development of the perimeter formula Diameter times  CIRCUMFERENCE AND CERCLE Will it be a circle or will it be a circumference? Neither one nor the other And then, what is it? Is it possible I don’t know what a sphere is? A beach ball

19. E XAMPLE Area = r 10cm I t is always an approximate value

20. E XA M P L E Length = r 5cm It is always an approximate value