Step-by-step explanation:
We know that the length of the diagonals will be more than the side.
Lets suppose the quadrilateral is a rectangle, with sides 6 and 4.
The length of a diagonal is:
√(6*6)+(4*4)
√36+16
√52
7.21(rounded off to 3 sig. fig.)
So, 6+4+6+4<2(7.21+7.21)
20< 2*14.42
20<28.84, which is true.
:)