Question

which equation is NOT an identity?
A)tan(-x)=-tan(x)
B)tan t(csc t+cot t)= sec t+1
C)sin tcot t=cos t
D)cos^2t-sin^2t=-1

Answer 1

the first one is, since tangent is odd

Answer 2

does the last one say
\[\cos^2(t)-\sin^2(t)=-1\]?

Answer 3

if so, pick that one since that is certainly not always the case

Answer 4

yes, it does

Answer 5

you were right. ty so much

Answer 6

for example if cos(t)=1 and sin(t) = 0, then 1-0=1 not -1
that is not an identity
yw