Answer:
No it is not a square.
Step-by-step explanation:
A square has 4 equal sides and 1 right angle (which means 4 right angles.
The Pythagorean Theorem would result is
19^2 + 19^2 = 722 if the figure was a square.
Since the diagonal of this figure is 20. 62^2 = 415.2, the diagonal isn't log enough for the figure to be a square.