Answer:
BD = 8.5 units
Step-by-step explanation:
From the figure attached,
ΔABC and ΔADB are the right triangles.
By applying mean proportional theorem,
BD² = AD × CD
BD² = 6 × 12
BD = √72
BD = 6√2
= 8.485
BD ≈ 8.5 units
Therefore, measure of segment BD will be 8.5 units.