# Who loves geometric inequality?

**Geometry**Level 3

Let **S** be a square of unit area, consider any quadrilateral which has one vertex on each side of **S**. If \(a, b, c\) and \(d\) denote the length of sides of the quadrilateral. Find the minimum value of \(a^2+b^2+c^2+d^2\)

Special Credit : Find the maximum value too.