## tahtah99 Group Title 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 2 years ago 2 years ago

1. darthsid Group Title

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

2. tahtah99 Group Title

mmm im not sure

3. tahtah99 Group Title

b*h

4. darthsid Group Title

|dw:1331785747771:dw|

5. darthsid Group Title

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

6. darthsid Group Title

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

7. darthsid Group Title

Now, if the new height is decreased by two, so it is h-2 so the area is : P x (h-2)

8. darthsid Group Title

are you understanding so far?

9. tahtah99 Group Title

yessss

10. darthsid Group Title

$P \times ( h-2) = P \times h - P \times 2$

11. tahtah99 Group Title

so it would be D ?

12. darthsid Group Title

But, P x h is the area of the original prism! the above equation basically says: New Area = Old Area - P x 2

13. darthsid Group Title

No, P x 2 means Perimeter times 2

14. tahtah99 Group Title

b?

15. darthsid Group Title

yeah, it's B

16. tahtah99 Group Title

thank you once again : )

17. darthsid Group Title