Respuesta :

Answer:

Given

  • ΔABC with ∠A = 90°
  • ΔADC with ∠D = 90°
  • The two triangles share same angle ∠C

With two same angles the triangles are similar according to AA similarity postulate:

  • ΔABC ~ ΔDAC

As we know if triangles are similar then their corresponding sides have same ratio:

  • AC/CD = BC/AC ⇒ AC*AC = BC*CD ⇒ AC² = BC*CD