Respuesta :

we know that

The Triangle Inequality Theorem, states that the sum of the lengths of any two sides of the triangle is greater than the length of the third side

so

[tex]AB+AC > BC\\AB+BC > AC\\AC+BC > AB[/tex]

we have

[tex]AB=12\ units\\AC=15\ units\\ BC=x\ units[/tex]

substitute the values

[tex]12+15 > x[/tex] ----->[tex]x < 27\ units[/tex]

[tex]12+x > 15[/tex] -----> [tex]x > 3\ units[/tex]

[tex]15+x > 12[/tex] -----> [tex]x > -3\ units[/tex]

[tex]3\ units < x < 27\ units[/tex]

therefore

the answer is

The value of x must be greater than [tex]3[/tex]

Answer:

x must be greater than 3

Step-by-step explanation:

If ABC is a triangle with sides a,b and c.

Then, it must satisfy:

a<b+c , b<a+c and c<a+b

Let a=12,b=15 and c=x

Then,  12<15+x , 15<12+x and x<12+15

i.e. -3<x , 3<x and x<27

Hence, x must be greater than 3 and less than 27 so that all the conditions are satisfied.

Hence, x must be greater than 3