Question 1052535
.
"The triangle inequality" requires that any of the tree sides of a triangle is shorter than the sum of the lengths of the two other sides.


In your case 60 = 20 + 40.
The side of 60 cm length is NOT shorter than the sum of the lengths of the two other sides (20 and 40).


On the "triangle inequality" see the lesson

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/Points-lines-and-rays/Points-and-Straight-Lines-basics.lesson>Points and Straight Lines basics</A>

in this site.