Sec A = t+1/t-1?

Question

Given that sec A = t+1/t-1 and angle A is in the fourth quadrant determine an expression for sin A. 

I have a test coming up but can't figure out this question.

Answer 1

But secA = 1/cosA

Angle A is in Fourth quadrant.So it is positive.

Apply formula : sin²A = 1 - cos²A