The factor of 11 is going to be 77 because you have to stay in between 70 to 80
and 7 times 11 is 77. It also has to be a number in the 11 timetables. It can't be 88 because we can't cross 80 so the factor is going to be 77.
Hope it helps
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
Answer:
C, 53.68 units
Step-by-step explanation:
tan 54° = 
39 tan 54° = x
x= 53.6788949 (just plug it in a scientific or graphing calculator)
x≈53.68