I'd say its D but im not quite sure, its what makes most sense to me.
Answer: second option.
Step-by-step explanation:
You must apply 
Then, given the right triangle and the angle D, the opposite side and the hypotenuse of the triangle are the following:

Therefore, when you substitute values, you have:

Reduce the fraction, then you obtain:

Answer:
I believe its c
Step-by-step explanation:
The domain of a quadratic function is all real numbers
It would be zero bc, 9x-7=-7 you do KCF Change the sign to addition so -7+7=0 now you divide 0 divided by 9=0. Hope this helps