1÷(tana-seca)-(1÷tana-seca)=-2sec
the way you typed it, I see ....
1/(tan a - sec a) - 1/tan a + sec a = -2 sec a
I tested this for 23° , and the LS ≠ RS, so it is not an identity.
Are you trying to solve this???
Before I attempt it, check the question to make sure you typed it
correctly following the order of operations