Question

answer above image in short

Answer 1

In ∆DAY & ∆CBX

since , Ax = BY (given) ,so , AX + XY = BY + XY , so AY = BX
DA = CB (GIVEN)

& ∠DAY = ∠CBX (90°)

By , SAS , they are congruent

Answer 2

given,
DA = CB
AX = BY
to prove :- ΔDAY ≈ ΔCBX
proof:- 
DA = CB
∠A = ∠B = 90°
AX = BY
therefore,
AX + XY = BY + XY
AY = BX (∵ if equals are added to equals the wholes are equal)
therefore ΔDAY ≈ ΔCBX 
by SAS congruence rule.
     i hope that this will help u.......................^_^