Answer: 
Step-by-step explanation:
Alright, lets get started.
The given expression is given as :

We know quotient identity as :

Similarly, we know reciprocal identity as :

lets plug the value of cot and sec in given expression

cos will be cancelled, remaining will be

Using reciprocal identity again, that will equal to :
................... Answer (A)
Um.... 368 369 370 371 372 372 374 375 376 377 378 379 etc
The Solution.
Representing the problem in a diagram, we have
By formula,

In this case,

Substituting these values in the formula above, we get

Clearing the bracket, we get



Dividing both sides by 2, we get

Therefore, the correct answer is option C.