2tan^2x - secx = 1
Plug in the values for secx and tanx.
First choice: secx = -1
means tan^2 x = 0
2(0) - (-1) = 1
Second choice: secx = 3 = hyp/adj
means tanx = √8
(Pythagorean theorem)
2(8) - 3 ≠ 1
Third choice: tanx = 3 = opp/adj
hyp = √(10)
means secx = √(10)
2(9) - √(10) ≠ 1
fourth choice:
tanx = -1 = opp/adj
means secx = √(2)
2(1) - √(2) ≠ 1
fifth choice: secx = 3/2
means cosx = 2/3 ; tanx = √(5)/2
2(5/4) - 3/2 = 1
Looks like the 1st and 5th choice work.