Question

in the diagram, \\(\overline{dg} \parallel \overline{ef}\\).

what additional information would prove that \\(defg\\) is an isosceles trapezoid?

\\(\bigcirc\\) \\(\overline{de} \cong \overline{gf}\\)
\\(\bigcirc\\) \\(\overline{de} \cong \overline{dg}\\)
\\(\bigcirc\\) \\(\overline{ef} \cong \overline{dg}\\)
\\(\bigcirc\\) \\(\overline{ef} \cong \overline{gf}\\)

Explanation:

Identify the given geometric properties

Using the Trapezoid Properties knowledge point

• The problem states that \(\overline{DG} \parallel \overline{EF}\).
• Since one pair of opposite sides is parallel, quadrilateral \(DEFG\) is a trapezoid.
• The parallel sides \(\overline{DG}\) and \(\overline{EF}\) are the bases of the trapezoid.
• The non-parallel sides \(\overline{DE}\) and \(\overline{GF}\) are the legs of the trapezoid.

Apply the definition of an isosceles trapezoid

• By definition, a trapezoid is an isosceles trapezoid if its non-parallel sides (legs) are congruent.
• The legs of trapezoid \(DEFG\) are \(\overline{DE}\) and \(\overline{GF}\).
• Therefore, to prove that \(DEFG\) is an isosceles trapezoid, we must show that \(\overline{DE} \cong \overline{GF}\).

Match with the given options

• Option 1: \(\overline{DE} \cong \overline{GF}\) (This states that the legs are congruent).
• Option 2: \(\overline{DE} \cong \overline{DG}\) (This relates a leg to a base).
• Option 3: \(\overline{EF} \cong \overline{DG}\) (This relates the two bases).
• Option 4: \(\overline{EF} \cong \overline{GF}\) (This relates a base to a leg).
• Thus, Option 1 is the correct choice.

Answer:

• (A) \(\overline{DE} \cong \overline{GF}\) (Correct answer)
• (B) \(\overline{DE} \cong \overline{DG}\)
• (C) \(\overline{EF} \cong \overline{DG}\)
• (D) \(\overline{EF} \cong \overline{GF}\)