Respuesta :

The first thing we must do in this case is to see that the triangles are similar.
 Therefore, we have the following trigonometric relationship:
 (4) / (y) = (y) / (12)
 We clear the unknown:
 y ^ 2 = 12 * 4
 y = root (48)
 y = root (3 * 16)
 y = 4raiz (3)
 Answer:
 
The value of y is:
 
y = 4raiz (3)