Triangle ABD and triangle CDB are similar because: -it is given that angle A and angle C are equal, both 90 -angle ABD and angle CDB are equal because they are alternate interior angles - side DB and side DB are the same length - two triangles are equal because of AAS
Since angles A and C are right angles, ΔABD and ΔCDB are right triangles
DB is common side, so
DB ≅ BD
AD ≅ CB is given
∠DAB ≅ ∠ BCD given
As per HL Postulate if the hypotenuse and leg of one right triangle are congruent to the hypotenuse and leg of another right triangle, then the two triangles are congruent