Prove that if the diagonals of a trapezoid are congruent, then it is an isosceles trapezoid. Given: BC || AD and AC DB Prove: ABCD is an isosceles trapezoid. Complete the two-column proof. Statements Draw BEL AD and CF 1 AD BE || CF BC || AD BCFE is a parallelogram BE=CF AC DB ZBED and ZCFA are right angles ABED ACFA ZBDE ZCAF ZCBDZBDE, ZBCA CAF ZCBD ZBCA BC BC AABC ADCB ZBAC LCDB ZBAD LCDA ABCD is isosceles Reasons C