For this case we have by definition, that each of the four internal angles of a square measure 90 degrees.
If we draw the diagonals of the square then the angles are divided by two, that is:
Thus, angle 3 measures 45 degrees.
By definition, the sum of the internal angles of a triangle is 180 degrees.
So:
Thus, angle 2 measures 45 degrees.
Answer:
45 degrees