Question

Can 6,12, and 18 make a triangle?

Answer 1

By definition, 3 side lengths are a triangle if any 2 side lengths add up to be greater than the third.

We can already see that the side lengths 6 and 12 will add up to a value of 18, which is equal to the last side length, meaning that the three values are not a triangle.

$a=6$

$b=12$

$c=18$

$a+b>c$

$b+c>a$

$c+a>b$

$6+12>18$ (Since this is not true, this is not a triangle)

Hope this helps.

頑張って!