Two sides of a triangle have lengths 11 and 18. What must be true about the length of the third side?

Ans:
We know that the sum of two sides of a triangle has to be greater than the 
third side.

If x is the 3rd side for this triangle,

x + 11 > 18, or x > 7

x + 18 > 11, or x > -7 (which is always true if the 1st condition is true)

Also, 11 + 18 > x, or 29 > x

So the 3rd side has to be greater than 7 and less than 29



Hope you got it :)