Answer:
1)
Given
2)

3)
Identities for tangent, secant and cosecant functions.
4)
Distributive property/

5)

6)

7)
Fundamental trigonometric identity/Existence of additive inverse/Modulative property/Distributive property
8)
Associative property/Existence of multiplicative inverse/Modulative property/Result.
Explanation:
Now we proceed to demonstrate by algebraic and trigonometric means the following trigonometric identity:

1)
Given
2)

3)
Identities for tangent, secant and cosecant functions.
4)
Distributive property/

5)

6)

7)
Fundamental trigonometric identity/Existence of additive inverse/Modulative property/Distributive property
8)
Associative property/Existence of multiplicative inverse/Modulative property/Result.