Which angle has the same measurement as angle DEA, and how do you know that the measurement is the same?

I don't know the exact answer but the correct answer would be A(Then, unknown value)E I think.

Step-by-step explanation:

The reason why is because it would make a square if you put the answer and ADE together.

THIS COULD BE WRONG

The answer would beDEA or AED, they are both the same. If you extend the two lines like I did, you can tell they are parallel. Angle C and angle A on ADE are congruent because they are corresponding, right angles are equal, so you are left with E and A on triangle ABC.

Yes, two vertical lines can be complementary