If we have a triangle with sides a,b,c then
b-a < c < b+a
describes the restriction of the length of side c, given sides a and b. This is due to the triangle inequality theorem.
a = 6
b = 9
b-a < c < b+a
9-6 < c < 9+6
3 < c < 15
Answer: The third side is between 3 cm and 15 cm. The third side cannot equal 3 cm, and it also cannot equal 15 cm.
