Compute area, perimeter, diagonal and inradius of a square from its side length.
A square has all four sides equal and all angles 90°. Its diagonal is s√2 and its inradius (inscribed circle radius) is s/2.
Area
A = s²
Diagonal
d = s√2
The diagonal is always √2 ≈ 1.414 times the side length.
Take the square root of the area: s = √A.