Answer:
y = 3[tex]\sqrt{7}[/tex]
Step-by-step explanation:
The 2 right triangles inside the right triangle are similar, then ratios of corresponding sides are equal, that is
[tex]\frac{y}{9}[/tex] = [tex]\frac{7}{y}[/tex] ( cross- multiply )
y² = 63 ( take the square root of both sides )
y = [tex]\sqrt{63}[/tex] = 3[tex]\sqrt{7}[/tex]
