Respuesta :

gmany

Triangle ADC and triangle BCD are similar, therefore the sides are in proportion:

[tex]\dfrac{y}{9}=\dfrac{7}{y}[/tex]

cross multiply

[tex]y^2=9\cdot7\to y=\sqrt{9\cdot7}\\\\y=\sqrt9\cdot\sqrt7\\\\y=3\sqrt7[/tex]

Answer: B. 3√7

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