Respuesta :
Using the triangle similarity postulates, you can verify that
[tex] \cfrac{12}{y}=\cfrac{y}{4}\\ \\ \Rightarrow y^2=48\\ \\ \Rightarrow y=\sqrt{48}=4\sqrt{3} [/tex]
Answer: The answer is A. 4 √3.
Step-by-step explanation: You may use the triangle similarity postulate and can verified that: [tex]\frac{12}{y}=\frac{y}{4}[/tex], [tex]y^{2}=\sqrt{48}[/tex], and [tex]y=\sqrt{48}=4\sqrt{3}[/tex]. I hoped this is very helpful, please mark me as brainliest, and have a happy holidays!!! :D