answer: the prove is mentioned below.
step-by-step explanation:
an isometric rigid transformation is a transformation of the plane that preserves lengths and angles.
that is, the pre-image and the image under a rigid transformation will be congruent.
here, given: cb ║ ed and cb ≅ ed
prove that: δ cbf ≅ δ edf
since, cb ║ ed
therefore, by the alternative interior angle theorem,
∠fcb ≅ ∠fed
∠fbc ≅ ∠ fde
and, cb ≅ ed ( given)
therefore, the angles and sides are persevered after transformation.
thus, by the definition of isometric rigid transformation,
δ cbf ≅ δ edf