In ∆ AOB OA + OB > AB — 1
( Sum of the length of any 2 sides of a triangle is greater than the 3rd side.)
In ∆ BOC
OB + OC > BC — 2 ( Sum of the length of any 2 sides of a triangle is greater than the 3rd side.)
In ∆ COD
OC + CD > CD — 3 ( Sum of the length of any 2 sides of a triangle is greater than the 3rd side.)
In ∆ AOD
OA + OD > AD — 4 ( Sum of the length of any 2 sides of a triangle is greater than the 3rd side.)
Add all the 4
