It equals 1 74/81 which is less than 3 4/9
Answer: option a.
Step-by-step explanation:
By definition, we know that:

Substitute
into the first equation, solve for the cosine and simplify. Then, you obtain:

As
then
:

Now we can find
:

7 plus 7 equals 14. Add one to that and you have 15 which is the answer.