contestada

Which equation is not an identity?


tan(–t) = –tan t



tan t(csc t + cot t) = sec t + 1



sin tcot t = cos t



cos2t − sin2t = –1

Respuesta :

Not 100% positive but i believe it is the third choice
Hey there, 

 Let t = 0 and you'd get 1 - 0 = -1 which is false 

I would go for (D)