Answer:
AB = 3.5 cm
Step-by-step explanation:
The volume (V) of the prism is calculated as
V = Ah ( A is the area of the triangular face and h the length of prism )
Here V = 84 and h = 12 , thus
12A = 84 ( divide both sides by 12 )
A = 7 ← area of Δ ABC
Thus
[tex]\frac{1}{2}[/tex] × 4 × AB = 7
2AB = 7 ( divide both sides by 2 )
AB = 3.5 cm
