The acceptable first step in simplifying the expression
is (a) ![\mathbf{\frac{tan\ x(1 - sec\ x)}{(1 + sec\ x)(1 - sec\ x)}}](https://tex.z-dn.net/?f=%5Cmathbf%7B%5Cfrac%7Btan%5C%20x%281%20-%20sec%5C%20x%29%7D%7B%281%20%2B%20sec%5C%20x%29%281%20-%20sec%5C%20x%29%7D%7D)
The expression is given as:
![\mathbf{\frac{tan\ x}{1 + sec\ x}}](https://tex.z-dn.net/?f=%5Cmathbf%7B%5Cfrac%7Btan%5C%20x%7D%7B1%20%2B%20sec%5C%20x%7D%7D)
To change the form of the expression, we simply perform several arithmetic operations on it.
Start by multiplying the expression by 1/1
![\mathbf{\frac{tan\ x}{1 + sec\ x} = \frac{tan\ x}{1 + sec\ x} \times \frac 11}](https://tex.z-dn.net/?f=%5Cmathbf%7B%5Cfrac%7Btan%5C%20x%7D%7B1%20%2B%20sec%5C%20x%7D%20%3D%20%5Cfrac%7Btan%5C%20x%7D%7B1%20%2B%20sec%5C%20x%7D%20%5Ctimes%20%5Cfrac%2011%7D)
Express 1 /1 as (1 - sec x)/(1 - sec x)
![\mathbf{\frac{tan\ x}{1 + sec\ x} = \frac{tan\ x}{1 + sec\ x} \times \frac{1 - sec\ x}{1 - sec\ x}}](https://tex.z-dn.net/?f=%5Cmathbf%7B%5Cfrac%7Btan%5C%20x%7D%7B1%20%2B%20sec%5C%20x%7D%20%3D%20%5Cfrac%7Btan%5C%20x%7D%7B1%20%2B%20sec%5C%20x%7D%20%5Ctimes%20%5Cfrac%7B1%20-%20sec%5C%20x%7D%7B1%20-%20sec%5C%20x%7D%7D)
Rewrite the above expression as follows:
![\mathbf{\frac{tan\ x}{1 + sec\ x} = \frac{tan\ x(1 - sec\ x)}{(1 + sec\ x)(1 - sec\ x)}}](https://tex.z-dn.net/?f=%5Cmathbf%7B%5Cfrac%7Btan%5C%20x%7D%7B1%20%2B%20sec%5C%20x%7D%20%3D%20%5Cfrac%7Btan%5C%20x%281%20-%20sec%5C%20x%29%7D%7B%281%20%2B%20sec%5C%20x%29%281%20-%20sec%5C%20x%29%7D%7D)
Hence, the acceptable first step is (a)
Read more about trigonometry ratios at:
brainly.com/question/24888715