ITF simplification

Express $\tan^{-1}\left(\frac{\cos x}{1-\sin x}\right),\ \ -\frac{3\pi}{2}<x<\frac{\pi}{2}$ in the simplest form.
58 Replies
TeXit
TeXit2mo ago
Nimboi
No description
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Nimboi
NimboiOP2mo ago
expressing sin(x) and cos(x) in their tan(x/2) forms, I got here: $\tan^{-1}\left(\frac{1}{1-\tan^{2}\left(\frac{x}{2}\right)}\right)$
TeXit
TeXit2mo ago
Nimboi
No description
Nimboi
NimboiOP2mo ago
what now?
BlindSniper (BS)
hmmm gimme a sec cos(θ)/1-sin(θ) can be expresssed as tan(π/4+θ/2)
Nimboi
NimboiOP2mo ago
you're correct
BlindSniper (BS)
bro what is that domain given
Nimboi
NimboiOP2mo ago
they used a different method to do that
BlindSniper (BS)
send
Nimboi
NimboiOP2mo ago
camera doesnt work ill just tell you
BlindSniper (BS)
I just have in my notes as standard result alr
Nimboi
NimboiOP2mo ago
cosx = sin(pi/2 - x) 1 - sinx = 1 - cos(pi/2 - x) sin(pi/2 - x) = 2sin(pi/4 - x /2)cos(pi/4 - x/2)
BlindSniper (BS)
oh so just derivation of it alr got it
Nimboi
NimboiOP2mo ago
1 - cos(pi/2 - x) = 2sin^2(pi/4 - x/2)
BlindSniper (BS)
yeah alr nice u got it right?
Nimboi
NimboiOP2mo ago
yeah but can i proceed from here cuz i thought of that first
BlindSniper (BS)
hmmm
Nimboi
NimboiOP2mo ago
didnt think to express cos(x) as sin(pi/2 - x) and whatnot
BlindSniper (BS)
yeah me neither keep in mind tho
Nimboi
NimboiOP2mo ago
bet anyways for boards cant use that standard result as a standard result
BlindSniper (BS)
true
Nimboi
NimboiOP2mo ago
@BlindSniper (BS) made a typo its 1 - tan(x/2) in the denom $\tan^{-1}\left(\frac{1}{1-\tan\left(\frac{x}{2}\right)}\right)$
TeXit
TeXit2mo ago
Nimboi
No description
BlindSniper (BS)
oh makes sense I wasn't getting what you got ok lemme see
Nimboi
NimboiOP2mo ago
@BlindSniper (BS) made a mistake along the way just start from the original problem lol main thoda stupid
BlindSniper (BS)
wow r u state board or cbse
Nimboi
NimboiOP2mo ago
cbse lmao havent done good math in a while
BlindSniper (BS)
then thoda problem to zaroor hai state board u can directly write hmmmmmm
Opt
Opt2mo ago
Yo what's going on?
Nimboi
NimboiOP2mo ago
ignore the silly in the middle look at the problem on top i wanna do it by expressing sin and cos as their tan(x/2) identities if that'll somehow work
BlindSniper (BS)
tried to reverse it but getting nowhere
No description
Opt
Opt2mo ago
Hmmm
Nimboi
NimboiOP2mo ago
i got it
BlindSniper (BS)
nice tan(x/2) in terms of sinx and cosx but you would need to know the answer for this
Nimboi
NimboiOP2mo ago
yeah you get here and then
BlindSniper (BS)
lite le baap
Nimboi
NimboiOP2mo ago
1 = tan(pi/4)
BlindSniper (BS)
yeah sure but .
Nimboi
NimboiOP2mo ago
yeah the answer is pi/4 + x/2 ah ok you mean
BlindSniper (BS)
I'm saying would you have known the answer if you didn't see the solution?
Nimboi
NimboiOP2mo ago
hard to think of that without knowing its of that form?
BlindSniper (BS)
yeah
Nimboi
NimboiOP2mo ago
if i knew i had to remove the tan then maybe yes this is a neat trick it seems more thinkable to me than expressing cosx as sin(pi/2 - x)
BlindSniper (BS)
yea true ig but it kind of reminds me of the complex number questions
Nimboi
NimboiOP2mo ago
which ones?
BlindSniper (BS)
whhere you have to convert in terms of cistheta lemme get one rq
BlindSniper (BS)
here you take it as sin(pi/2-x) pretty fire
Nimboi
NimboiOP2mo ago
man what the how does one have that level of foresight or is it more just screwing around
BlindSniper (BS)
nah but this is easy in this case but if you get directly in a trigonometry question I wouldn't think of it
Nimboi
NimboiOP2mo ago
💀
BlindSniper (BS)
if you see it that way
Nimboi
NimboiOP2mo ago
well, thanks dude ill mark as solved
BlindSniper (BS)
👍
Nimboi
NimboiOP2mo ago
+solved @BlindSniper (BS)
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