Finding Volume of a Prism

[isu23pink]

okay, so i've done this problem numerous times, but apparently i keep getting the volume wrong!

this is what i did the first time:
(1/2)(4)(2rad3)12
= (1)(8rad3)
=48rad3 WRONG!

then i tried it again:
(1/2)(4)(3.5)12
= 84inches cubed WRONG ? my teacher said it was wrong.

 

[mmm4444bot]

(1/2)(4)(3.5)(12) = 84 inches cubed

my teacher said it was wrong.

The volume is the area of the triangular cross-section times the length, so it looks like you used the correct formula here; the volume is 84 cubic inches.

Perhaps, your teacher objects to your wording of the units. I dunno.