Question

The height of an equilateral rectangular prism decreases by two units. The new lateral area is less than the original by how much?
Answer
two times the area of the base
two times the perimeter of the base
two less than the the area of the base
two less than the perimeter of the base

I think it is C but im not sure

Answer 1

What's the formula for the area of the prism?

Answer 2

mmm im not sure

Answer 3

b*h

Answer 4

That's a rectangular prism. The lateral surface area is the area of the 4 sides, not including the base and the top.

Answer 5

so the formula for the lateral surface area is
Perimeter of base X height

Answer 6

Now, if the new height is decreased by two, so it is
h-2

so the area is :
P x (h-2)

Answer 7

are you understanding so far?

Answer 8

yessss

Answer 9

\[P \times ( h-2) = P \times h - P \times 2\]

Answer 10

so it would be D ?

Answer 11

But, P x h is the area of the original prism!

the above equation basically says:

New Area = Old Area - P x 2

Answer 12

No, P x 2 means Perimeter times 2

Answer 13

b?

Answer 14

yeah, it's B

Answer 15

thank you once again : )

Answer 16

Glad to help, good luck!