Since there is a barricade placed along the diagonal sq field, let's focus on one side of the triangle.
A pythagoras theorem formula can be used for right angle triangle.
So now we let the barricade be X.
By Pythagoras Theorem,
X² = 50² + 50²
X = sq root (50² +50²)
= 70.711 m ( 5sf)
= 70.7 m ( 3sf)
Therefore, the length of barricade is 70.7 m