Answer:
You have to apply Basic Trigonometric Identities :
[tex] {sec}^{2} (θ) = {tan}^{2} (θ)+ 1[/tex]
So for this question :
[tex] {sec}^{2} (a) - 1 - {tan}^{2} (a) = 0[/tex]
[tex]LHS = {sec}^{2} (a) - 1 - {tan}^{2}(a) [/tex]
[tex]LHS = {tan}^{2} (a) + 1 - 1 - {tan}^{2} (a)[/tex]
[tex]LHS = 0[/tex]
[tex] LHS = RHS \: (proven)[/tex]
