## Faman39 3 years ago You are making poster board boundary markers in the shape of square pyramids for a relay race. If you are including a 12 -inch square as the bottom and you want the slant height to be 14 inches, how much poster board do you need? 252 in2 420 in2 480 in2 532 in2

1. Faman39

@UnkleRhaukus can you able to help me ?

2. UnkleRhaukus

|dw:1352387741795:dw|

3. Faman39

I still cant get this, can you able go in bit detail ?

4. UnkleRhaukus

can you see how i flattened all the surfaces a plane?

5. Faman39

Yes

6. UnkleRhaukus

you have a square , and four big triangles,

7. Faman39

ok

8. UnkleRhaukus

the area of a square is the side length squared the area of a triangle is half of the base times the height

9. Faman39

Are we gonna....multiply 14 and 12?

10. Faman39

i am sorry i am totally talking wrong

11. UnkleRhaukus

yes the base of the triangles is 12 and they have a height of 14 , the area of each tringle is half these multiplied together

12. Faman39

but i got 168 ? :(

13. UnkleRhaukus

how?

14. Faman39

I do not know, probably i m doing wrong i know :(

15. Faman39

that must be for it

16. UnkleRhaukus

what did you get for the area of the square? and what did you get fo the area of each triangle ?

17. Faman39

i multiply 14 with 12 :(

18. UnkleRhaukus

the area of a triangle is HALF of the base times the height

19. Faman39

so half * 14 * 12

20. UnkleRhaukus

what do you get?

21. Faman39

84 :(

22. UnkleRhaukus

right so , one triangle is 84 in^2 what is the area of the square

23. Faman39

12?

24. UnkleRhaukus

the area of a square is the side length squared $12^2=$

25. Faman39

14 ?

26. Faman39

27. UnkleRhaukus

$12^2=12\times12=$

28. Faman39

144

29. UnkleRhaukus

right

30. UnkleRhaukus

the total area is made up of 4 triangles and one square ,

31. Faman39

So we divide 4 with 144 ?

32. UnkleRhaukus

add the area of the square to four times the area of the triangle

33. Faman39

Still not getting any correct point

34. Faman39

i am so sorry, i m horrible that i m getting wrong answer

35. Faman39

144 * 12 * 4 ?

36. UnkleRhaukus

$A_{\text{square}}=12 [\text{in}]\times12 [\text{in}]=144 [\text{in}]^2$ $A_{\text{triangle}}=\frac{14 [\text{in}]\times12 [\text{in}]}2=84 [\text{in}]^2$ $SA_{\text{square pyramid}}=A_{\text{square}}\quad+\quad4\times A_{\text{triangle}}$

37. Faman39

Thank you so so much @UnkleRhaukus, your so awesome and genius!!!!!

38. Faman39

thanks alot! And i m sorry for troubling :(

39. Faman39

i know, i m totally pain, cuz i barely understand thing

40. UnkleRhaukus

i hope it makes some sense now, can you tell me how much poster board do you need?

41. Faman39

480 in2

42. UnkleRhaukus

$\color\red\checkmark$

43. Faman39

Thank you so much @UnkleRhaukus !!! your too great!!!!!!