Which of the following are trigonometric identities ? check all that apply. tan^2 x -

I hope you are looking for these answer choices as you have not posted the choices. Therefore, I have a similar question with these answer choices.

a). tan² x - 1 = sec²x
b). 4 cosxsinx = 2cos + 1 -2sinx
c). tanx cosx cscx = 1
d). 1- tanx tany = cos(x+y) ÷ cosx cosy

Options B, C, D are correct because, for all them, left-hand side equals to the right-hand side for x = 0.

The option A)
tan² x - 1 = sec²x is not true. 
since x = 0
Therefore,
The Right hand side would be:
                                         tan² x - 1 = sec²(0)
                                                             = 1
The Left hand side would be:
                                                    tan² x - 1 = tan² (0) - 1
                                                                   = 0 - 1
                                                                   = -2
Therefore,
Both sides are not equal so it's not a trigonometric identity.

Iwould say false, not positive but if prices went up for both stores, technically there will be less buyers?

Ithink it is correct but just ask someone else but i am sure it it