Two sides of a triangle measure 8 cm and 15 cm. which could be the length of the third side? 6 cm 18 cm 24 cm 28 cm

The correct answer is:  [B]:  "18 cm ". 

Explanation:

If a, b, c are the three (3) sides of triangle,  then: 

a − b < c > a + b ;  (a ≥ b)

Let "c" = the "third side" ; 

Let "b" = the "first side" ;  {since:  "(a ≥ b)" ;  → "(15 cm ≥ 8 cm)" } ;

Let "a" = the second side" ; {again; since:  "(a ≥ b)" ;  → "(15 cm ≥ 8 cm)" } ;

→ a − b < c > a + b ;  (a ≥ b) .

So;       "side a" = 15 cm ; 

             "side b" =  8 cm ;

             "side c" = the "third side" ; 

→ 15 cm − 8 cm < c > 15 cm + 8 cm ; 

→  7 cm < c > 23 cm ; 

Consider the answer choices: