Which of the following are identities? check all that apply.

Options A and D.

Step-by-step explanation:

To check the identities we have to check each option given.

A. tan(x - π) = tanx

We take left hand side (L.H.S.) of the equation.

tan(π - x) = tanx [ since we know tan(π ± x) = tanx ]

So L.H.S. = R.H.S.

It's an identity.

B. sin(x + y) + sin(x - y) = 2cosx siny

We take L.H.S. first

sin(x + y) + sin(x - y)

= sinx coxy + siny cosx + sinx cosy - cosx siny

= 2sinx cosy ≠ R.H.S.

Option B is not an identity.

C. cos(x + y) - cos(x - y) = 2cosx cosy

We take L.H.S. of the equation.

cos(x + y) - cos(x - y) = cosx cosy - sinx siny - (cosx cosy + sinx siny)

= -2sinx siny ≠ R.H.S.

Therefore, option C is not an identity.

D. cos(x + y) + cos(x - y) = 2cosx cosy

We take L.H.S. of the equation.

cos(x + y) + cos(x - y) = cosx cosy - sinx siny + cosx cosy + sinx siny

                                  = 2cosx cosy = R.H.S.

Therefore, option D is an identity.

Options A and D are the identities.

b. t=-25h+3

step-by-step explanation:

answer:

probably the same as it is today since you did not eat the corn dogs yet

step-by-step explanation: