I really need help in connections Geometry Unit 5 lesson 9 Surface Area and Volume Unit test please?!?!? Im having a really hard time and anyone willing to help it would be greatly appreciated!!

Question

moonlitfate · Answer

Can you give an example of one of the problems that you're having issues with?

anonymous · Answer

I'm basically having issues with most of them. Math definitely isn't my stronger subject.

anonymous · Answer

Find the lateral area and surface area of the cone. Round the answers to the nearest tenth. The figure is not drawn to scale.
  (1 point)
L.A. = 395.8 ft2; S.A. = 791.7 ft2
L.A. = 1,583.4 ft2; S.A. = 1,244.1 ft2
L.A. = 622.0 ft2; S.A. = 791.7 ft2
L.A. = 791.7 ft2; S.A. = 1,244.1 ft2

anonymous · Answer

attachment

anonymous · Answer

That's only one of them.

moonlitfate · Answer

Okay, well' let's do that one first. :)

anonymous · Answer

Please. xD

moonlitfate · Answer

|dw:1367446549397:dw|-- So, I flipped the cone there.  And if you look at the cone, the base is a circle.  And if you draw a line from the radius to the top of the cone, you get a triangle.   Do you see that?  [And sorry if my explanations aren't so great; not so great with Geometry]

anonymous · Answer

That's alright- me either, obviously!
Yes, I see it. Isn't there a formula for calculate the surface and linear areas of a cone though?
I was having a hard time recalling it.

moonlitfate · Answer

Yes. :)

anonymous · Answer

Do you know what the formulas are?

moonlitfate · Answer

Surface Area of a cone is:$$SA = \pi r s + \pi r^2$$
It's basically the area of the base and the area of the cone added together. r = the radius, and s = the side of the that we were given.

anonymous · Answer

Okay, so I can try to solve it then.

anonymous · Answer

r = 12
s = 21
3.14 x 12 x 21 = 791.28

anonymous · Answer

3.14 x 12^2 = 3.14 x 144
3.14 x 144 = 452.16

moonlitfate · Answer

Lateral Area of a cone is: $$LA = \pi r L$$

where r is the radius, L is the slant height of the cone.

anonymous · Answer

wouldn't the slant height be 21?

anonymous · Answer

I believe that the answer is D. Thanks for your help. (:

moonlitfate · Answer

$$SA = \pi(12)(21)+\pi(12)^2$$$$=791.681 + 452.389$$
= 1244.1

And yes, the slant height is 21. :)

anonymous · Answer

Thanks for your help (:

moonlitfate · Answer

You're welcome  Does it make sense now?