Answer :
Multiply both
LHS u will get identity and RHS u will get xy
Finally ur answer
Sec A + Tan A = x
Sec A - Tan A = y
multiply the above LHS :
(sec A + Tan A) (Sec A - Tan A) = x y
Sec² A - Tan² A = x y
1 = xy
Sec A - Tan A = y
multiply the above LHS :
(sec A + Tan A) (Sec A - Tan A) = x y
Sec² A - Tan² A = x y
1 = xy