Question

how do you find a area of a prism?

Answer 1

If you're trying to find the volume, find the area of one of its faces (triangle, square, octagon, etc), then multiply this by the length ( the 3rd dimension). In other words, Surface Area of Face * Length = Volume.

If you'rel looking for surface area, take the surface are of one face, multiply by 2 (for two facs). Then you can find the rest of the SA in two sort of different ways.
1) treat each side of the length of the prism as a separate rectangle. For example, if I had a prism with a triangular base with side lengths 3-4-5 and the prism length 6, I would have 3 different lengthwise rectangles of 3x6, 4x6, and 5x6.

2) find the perimeter around one face (3+4+5), then multiply this by the prism length. Hopefully you can tell that mathematically this is equivalent to 3x6+4x6+5x6. In 3 dimensions, its like 'unrolling' the prism out to be a flat 2D rectangle.

Does this make sense?

Answer 2

it's confusing... i don't understand it :(

Answer 3

Which part do you not understand? You have to tell me what is confusing and what you understand, then I can help you understand it better! :)

Answer 4

i need help with what i'm supposed to add or multiply

Answer 5

Here's an example. You have a triangular prism with triangle side lengths 3, 4, and 5, with prism length 6.


to find the volume of this, you find the surface area of the face. The area of a triangle is base * height*1/2 (and 3-4-5 is a right triangle), so 3*4*1/2 = 6 units^2
Then the prism length is 6 units.
volume = surface area of face * length of prism, so V= 6 units^2 * 6 units = 36 units ^ 3

Surface area:
SA of the faces, there are two faces. 2* 6 units^2 = 12 units ^2
SA of the lengthwise pieces, there are three of them. This can be found as 3 separate rectangles, 3x6, 4x6, and 5x6. This adds up to 72 units ^2 for all three rectangles.

total SA = SA of faces + SA of lengthwise pieces = 12 units ^2 + 72 units ^2 = 84 units ^2.

Let me know if you're still confused about anything!

Answer 6

Kat_Cat7 - do you have an actual problem to solve?

Answer 7

no all it says is how do you find area in a prism

Answer 8

one more question, whats SA?

Answer 9

Wow since cathy did so much work, I'll leave this question.

Answer 10

SA is the abbreviation for Surface Area.

Answer 11

ohh

Answer 12

and thank you guys so much :)

Answer 13

@Kat_Cat7 no more confusion? I'm here to help - let me know!

Answer 14

there is a little confusion but i'm writing down notes

Answer 15

Okay. You can @ me in this thread if you have followup questions related to this, if you want. I'll be logged in for a little longer.

Answer 16

ok