## tahtah99 3 years ago 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

1. darthsid

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

2. tahtah99

mmm im not sure

3. tahtah99

b*h

4. darthsid

|dw:1331785747771:dw|

5. darthsid

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

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

7. darthsid

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

8. darthsid

are you understanding so far?

9. tahtah99

yessss

10. darthsid

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

11. tahtah99

so it would be D ?

12. darthsid

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

No, P x 2 means Perimeter times 2

14. tahtah99

b?

15. darthsid

yeah, it's B

16. tahtah99

thank you once again : )

17. darthsid