Answer:
Step-by-step explanation:
Since it is a square, a line from one corner to the other cuts the right angles in half. this is only because it is a square, if you don't see why I can explain.
Since each right angle is cut in half each smaller angle on the corners is 45 degrees.
ABD is one of those cut in half angles, specifically from the right angle ABC. So it is 45 degrees
