In triangle XYZ, the length of side XY is 21 mm and the length of side YZ is 31 mm. Which of the following could

be the length of side XZ?

There are two possible answer answer is this problem since no diagram is given

First if XZ is the longest side

XZ < Xy + YZ

XZ < 31 + 21

The possible length of XZ = 51 mm

If XZ is not the longest length

YZ < XZ + XY

31 < 21 + XZ

So the possible length of XZ = 11 mm