anonymous 4 years ago Dana plans to cover this model of a half moon completely with silver foil. How many square centimeters of silver foil would Dana need to cover the model completely? 402.2 536.2 603.4 150.8

1. anonymous

2. anonymous

Dude, this is a homework help site, do not ask for emails :P

3. anonymous

its not and ur a player

4. anonymous

true @trackzz

5. campbell_st

well the surface area of a hemisphere is $SA = \frac{1}{2}(4pir^2) + \pi r^2$ and you have a radius of 8 cm just substitute and solve.

6. anonymous

i dont know how to do that

7. anonymous

cause i just see leters

8. anonymous

@campbell_st

9. campbell_st

ok... do you have a calculator ?

10. anonymous

yesss

11. campbell_st

ok you need to type in $0.5 \times 4 \times \pi \times 8^2 + \pi \times 8^2$ that will give the answer to covering the hemisphere in foil..

12. anonymous

Alrii so basically what campbell has show you is the surface are of a sphere. Any problem in which they ask for something that wraps around a specific shape involves surface are. The surface area of a sphere is: 4 pi r^2 Where r is the radius of the sphere.

13. anonymous

what is p 12.18 or 12.14

14. anonymous

If you're familiar with the button pi, it is the value of 3.14. Now for this particular question, it is a hemisphere. So half the surface are of the sphere. 1/2*(4pi r^2) = SA

15. anonymous

thnks

16. anonymous

@crystal1 what are you talking about>

17. anonymous

you said:" what is p 12.18 or 12.14" what do you mean?

18. anonymous

19. anonymous

20. anonymous

wait

21. anonymous

22. campbell_st

nope... thats a long way from being correct

23. campbell_st

did you type in the equation I gave you as its written...?

24. anonymous

Shall we break it down Campbell? I think it's the BEDMAS

25. anonymous

Alright crystal, I want you to do r^2 first. Find the value of the radius squared.

26. anonymous

yes i did @campbell_st

27. campbell_st

and tracks... I think you possible solution is missing the circular base... as the question talks about competely covering... it

28. anonymous

you guys lost me now im confuse

29. campbell_st

ok... lets to it in little bits can you calculate $0.5 \times 4 \times \pi \times 8^2$

30. anonymous

Ok my bad, alrii yeah you're right. I'll leave this to Campbell. Dont wanna confuse you,

31. campbell_st

@crystal1 did you get an answer for the new calculation..?

32. anonymous

b

33. campbell_st

what was the number..?

34. anonymous

i dont reaally know im sorry im dumb i dont know how to start this thats why i need help

35. anonymous

You're not dumb. Tell yourself you're smart. You'll get the answer. Crystal, you got this. Wake up, look at what campbell wrote for you.

36. anonymous

37. anonymous

you're not finished yet. Add the pi r^2 to what you got to get the answer

38. campbell_st

nope thats only the 1st part of the problem the curved surface has an area of 402.2 cm^2 now you need to find the area of the circular base... $\pi \times 8^2$

39. campbell_st

you need to calculate this number...

40. campbell_st

then the final answer will be $402.2 + \pi \times 8^2 =$

41. anonymous

6485.44

42. campbell_st

wow... nope not it lets make it easier what is $\pi \times 8^2 =$

43. anonymous

75.36

44. campbell_st

nope still not right... $\pi \times 8^2 = 201.1$

45. anonymous

how do you get thaat i tough that 8x2 its = 24

46. campbell_st

do you know how to square a number...

47. anonymous

no

48. campbell_st

ok... then perhaps you need to ask you teacher... how to do the problem is you don't know the basics...

49. anonymous

thnks you @campbell_st