Which of the following sets of possible side lengths does not form a triangle

a) 5,6,10

b) 4,5,15

c) 22,21,42

d) 3,4,5

b) 4,5,15

Step-by-step explanation:

In a triangle of sides's length a, b and c

in order to be able to form (construct) this triangle we must have:

c - a < b < c + a

in fact this work with cases a), c) and d)

but not b)

because 15 - 4 is not < to 5

in other words 15 - 4 > 5