Total surface area of a cuboid when length is 6cm width is 4cm and height is 5cm

answer: as the alternate interior angles are congruent, the opposite

sides of quadrilateral abcd are parallel.

step-by-step explanation:

so, the missing phrase in elba's proof is: alternate

interior angles

let's break this statement up so we can find the answer:

by cpctc, angle abd is equal to angle cdb and angle adb is

equal to angle cbd.

since

angle abd is equal to angle cdb, this means that they are alternate interior angles

so, the correct answer would be: as the alternate interior angles are congruent, the opposite

sides of quadrilateral abcd are parallel.

two interior angles which lie on opposite sides of a

transversal   and on different parallel

lines and are called alternate interior angles.

its either a or d. do u have any other information? ?