1. 4
2. 8
These are the only possible answers
I am sorry but this is incomplete. If you would like to PM me the full question I would love to help?
SOLUTION
Given the question in the image, the following are the solution steps to answer the question.
STEP 1: Explain the formula to use
Using the cosine rule which states that:

STEP 2: Write the given sides

STEP 3: Find the value of z

Hence, the indicated length is 4.0
1400, as 1200 + 200 = 1,400 and 1600 - 200 = 1400.