# Thread: finding surface area and volume

1. ## finding surface area and volume

hI,
i am looking for some help!
I need to figure out the surface area of a 2cm cube, with dimensions length, width and height all 2cm. My answer is 0.0012 m squared... Is this right? I have no idea!

A 4cm cube with length, height and width all 4cm. My answer is, surface area= 0.0024 m squared. Again not sure if I'm on the right track...

A rectangular prism with length 4cm, width 3cm and height 6cm. My answer is, surface area= 24 millimetres which just doesn't seem right.

A rectangular prism with length 12cm, width 9cm and height 6cm. My answer is, surface area= 648 millimetres. Again doesn't seem right!

And then theres the cylinders...
I need to find the surface area of two. The first has a radius of 1cm and a height of 3cm. The second has a radius of 4cm and a height of 12cm.

If you can provide me with any tips on how to find volume too, I would be very grateful. All basic stuff I know, but I just can't figure this stuff out!

2. Originally Posted by bookbaby84
I need to figure out the surface area of a 2cm cube, with dimensions length, width and height all 2cm. My answer is 0.0012 m squared... Is this right? I have no idea!
for a cube

$\displaystyle SA = 6L^2$

so

$\displaystyle SA = 6(2)^2 = 6\times 4 = 24 cm^2$

3. Originally Posted by bookbaby84

A 4cm cube with length, height and width all 4cm. My answer is, surface area= 0.0024 m squared. Again not sure if I'm on the right track...
Try the above method for this guy!

4. Originally Posted by bookbaby84

A rectangular prism with length 12cm, width 9cm and height 6cm. My answer is, surface area= 648 millimetres. Again doesn't seem right!

For a rectangular prism

$\displaystyle SA = 2(LW+WH +LH)$

where $\displaystyle L= 12$ $\displaystyle W=9$ & $\displaystyle H=6$

$\displaystyle SA = 2(12\times 9+9 \times 6 +12\times 6)$

$\displaystyle SA = 2(108+54 +72)$

$\displaystyle SA = 2(234)$

$\displaystyle SA = 468cm^2$

Try it yourself on the problem below

Originally Posted by bookbaby84

A rectangular prism with length 4cm, width 3cm and height 6cm. My answer is, surface area= 24 millimetres which just doesn't seem right.

5. Originally Posted by bookbaby84

And then theres the cylinders...
I need to find the surface area of two. The first has a radius of 1cm and a height of 3cm. The second has a radius of 4cm and a height of 12cm.
For a cylinder

$\displaystyle SA = 2\pi r(h+r)$

$\displaystyle SA = 2\pi \times 1(3+1)$

$\displaystyle SA = 2\pi (4)$

$\displaystyle SA = 25.12cm^2$

Now have a crack at the second one!

6. er the guy above... do you have to post your answer to him in 3 separate posts?

Anyway, i am not telling you the answers since its rather easy. so i tell u how to do it.
1) Go google and type like "surface area rectangular prism" volume anything just type inside and you will get the formula. Its readily available
2) Draw the shape out yourself and visualize how to find the surface area. Like the cube example, its made up of 6 similar square sides. So just find 1 surface area of the square and multiply by six.

7. Originally Posted by Singaporean
er the guy above... do you have to post your answer to him in 3 separate posts?
Sometimes, depends if i'm at work or not.

8. Oh, I see! You do one quick answer and post it while your boss is not looking!

9. Yeppers!

10. ## Thanks!

Thanks so much for helping me! Very appreciative!