If we are in Euclidean Space, then it is never possible for the sum of the lengths of two sides of a triangle to be less than the length of the third side.
From this, we can reckon that one side of a triangle is always less than or equal to the sum of the lengths of the other two sides.
Algebraically, we can write this as an equation where d(p,q) for the function to calculate the distance between points p and q:
If you have taken a class in Geometry you may prefer:
[latch]\overline{AB} := length of the line segment between point A and point B [/latch]
Vectoreverything 