|a| means the modulus of the vector a, or basically if it is postive it stays the same, and if it is negative u multiply it by -1.

If then:

|a|+|b| = |a+b|

if then:

|a|+|b| = |a+b|

However if and or and then:

|a|+|b| > |a+b|

So thats why For any 2 vectors a and b , |a| + |b| is always greater than or equal to |a+b| .