Three junior high school math problems congruent triangles. . Tonight will be fine, it's urgent ~ ~ ~ ~ ~

Prove,

Because all triangles ABC are equal to triangle DEF, the corresponding sides are also equal, that is, AB=DE.

Therefore, AD =AB-BD=DE-BD=BE.

Prove,

Because all triangles ABD are equal to triangles ACE, the corresponding angles are equal, that is, angle ADB= angle AEC.

So angle 1 = 180 degrees-angle ADB = 180 degrees-angle AEC= angle 2.

Solution, because all triangles ABC are equal to triangle ABD, and angle C= angle D.

Because angle A=90 degrees is in the triangle ACD, angle C+ angle D = 180-90=90 degrees.

So the angle C = 90/2 = 45 degrees.

And because the angles corresponding to the two triangles are equal, the angle CAB= the angle BAD.

And angle CAB+ angle BAD= angle CAD=90 degrees, so angle CAB= angle BAD=45 degrees.

So the angle ABC = 180- angle BCA- angle CAB= 180-45-45=90 degrees.

Same angle DBA=90 degrees.

So AB vertical CD