Answer
The guy above me is correct but I'm gonna explain it better
Explanation:
Step ONE 1.- Arrange the equation: Choose an equation from the LAW OF COSINES.
8.1^2= 7.1^2 + 4.2^2 - 2(7.1)(4.2) COS(T)
Step 2- Solve
65.61= 68.05-59.64 x COS(T)
Step 3- Inverse Operation (SUBTRACT: 65.61-68.05)
65.61= 59.64 x COS(T)
-68.05
INVERSE OPERATION AGAIN (DIVIDE: -2.44/59.64)
-2.44/59.64= COS(T)
INVERSE OPERATION ONE LAST TIME
WE MUST GET THE "T" ALONE SO WE MUST MOVE THE "COS" TO THE OTHER SIDE "COS^-1 (Cos (x))
Cos ^-1 (-.04)= (T)
87.707= T
ROUND: ROUND 87.707 TO THE NEAREST DEGREE.
88 = T