Question

What is the total area of the interior faces of this composite solid?

Answer 1

can someone please help me ?

Answer 2

Is there a particular face you have a problem calculating for?

Answer 3

i got 392 ?

Answer 4

I'm sorry, can't do the whole calculation right now =). So you are comfortable with calculating for all the faces? That is my primary concern.

Answer 5

If i multiply 7*7*8 that equals 392 and that is not one of the options so im confused if im doing it right

Answer 6

I think I know the problem. Why are you multiplying 7*7*8 ?

Answer 7

Because if your finding the area, then arnt you multiplying ?

Answer 8

Yes, multiplication is used when finding area. But it is also used when finding volume. What will multiplying 7*7*8 give you?

Answer 9

It will give you the volume of part of the solid. right?

Answer 10

yeah but the other part of the solid you would do the same thing ?

Answer 11

Nope. We want area. Not volume. Are you familiar with calculating the surface area of a solid?

Answer 12

No.

Answer 13

You need that knowledge to tackle this question. I will give you an example, then you will read more on the topic. Okay?

Answer 14

okay.

Answer 15

Example A. Calculate the surface area of the following composite solid:

Answer 16

That is a cube. Now, when we are asked for the surface area, we want the total area of all the faces of the cube. All the faces of a cube have equal area, and a cube has 6 faces. The area of one face is 4*4=16. Thus the surface area = 16*6=96.
Does that make sense?

Answer 17

Yes. That makes sense. it made me understand the problem better.

Answer 18

Good. A little more practice should make it much clearer. I wish you all the best.

Answer 19

thank you.

Answer 20

You're welcome :)