Question

It's not possible to build a triangle with side lengths of 7, 6, and 9.
A. True
B. False

Answer 1

Triangle inequality theorem :)
Take the two 'lesser' sides, if their sum is greater than the third, then you can form a triangle from them :D

Answer 2

remember that in a triangle ABC with sides AB, BC and CA

it is important that
AB + BC > CA

SO SEE IF THIS IS SATISFIED HERE

and here AB AND BC are the smaller sides