Answer:
or 
Step-by-step explanation:
we know that
Applying the law of cosines

In this problem we have



substitute the values



Answer:

Step-by-step explanation:

Withdrawals must be subtracted from the beginning balance since to withdraw means to take out, so withdrawing money would lower the balance.
Deposits are added to the balance, so they must be added in the equation.
The answer is <span>c) Beginning Balance - Withdrawals + Deposits = Ending Balance</span>