TAN t = 1/ SEC t , right?

[HannibalTheCannibal]

Well? Then COS t = 1/ SEC t

Can anyone refresh me on the six trig functions?

 

[MrDudeMan]

sin x = 1/csc x
cos x = 1/sec x
tan x = 1/cot x

so no, tan x does not equal 1/sec x

 

[TomKazansky]

tan x = sinx / cosx

 

[Ze]

also if you need these:

sin^2(x)+cos^2(x) = 1
tan^2(x) + 1 = sec^2(x) <-- i think this was what you were thinking of in some sense
cot^2(x) + 1 = csc^2(x)
sin^2(x) = (1 - cos2x) / 2
cos^2(x) = (1 + cos2x) / 2

 

[MrDudeMan]

also sin 2x = 2sin x*cos x

 

[damonpip]

secx = 1/cosx, so 1/secx = cosx
tanx = sinx/cosx
cscx = 1/sinx

 

[cquark]

You can use the Euler formula e^ix = cos(x) + i sin(x) to get identities for sin() and cos() in terms of complex exponentials, then the other identities fall out easily.