Multiply through by then apply the Pythagorean identity to get a quadratic in .
Knowing that: tan^2x + 1 = sec^2x, sec^2x = 1/cos^2x and also sin^2x + cos^2x = 1, is what is required to answer this question.
More specifically begin by getting everything in terms of sin x and cos x and hopefully it will become much easier to manipulate.