Answer:
BA = 12
Step-by-step explanation:
All the right triangles are similar, so the ratio of hypotenuse to long side is a constant. In particular ΔABC ~ ΔDBA, so ...
hypotenuse/long-side = BC/BA = BA/BD
Cross multiplying gives ...
BA² = BC·BD
BA = √(BC·BD) = √(16·9)
BA = 12
