How do you find dimensions on a square ?

Question

never learned how .

there is a square type figure top part is labeled 30/40 and the side is 49/40

Answer 1

This certainly does not seem to be a square.   It may be a rectangle with two sides of 30/40 or 3/4 and two sides of 49/40.   (49   fortieths)

Answer 2

A square has 4 equal sides, and 1 included angle of 90 degrees.(thus the 3 others also  are 90 deg).

So we don't know what you're looking at.