Work: To find surface area, you find the area of each side and add it all together. For the bottom and the top sides, it’s 6 x 3 which equals to 18. 18 + 18 = 36. Then, 3 x 4 = 12. 12 + 12 = 24. 6 x 4 = 24. 24 + 24 = 48. Then, you add it all together which equals to 108. If what I did doesn’t makes sense, I’ll explain it more detailed here.
So, I found the area of the bottom side and multiplied it by 2 to represent the top and bottom sides. Then, I did the same thing for the other sides if that makes sense. I’m really sorry if I’m not explaining it well. I’m better at doing the work in my head and not on paper or explaining it to other people.
We assume the opposite and then get to a point where we get a false statement. That proves that the the opposite of the opposite (What we originally wanted to prove) is true.
