Answer
13.1 millimeters
Step-by-step explanation
The volume of any regular object is found by;
Volume = base area × length.
In the question, the base is a triangle of height 12 millimeters and a base length L.
The length of the prism is 14.3 millimeters.
∴ Volume = base area × length.
1,123.98 = (1/2 × 12 × L) × 14.3
1,123.98 = 85.8 L
L = 1,123.98/85.8
= 13.1 millimeters