#is this an identity I’m not aware of with arctan?

48 messages · Page 1 of 1 (latest)

lone star
#

Wolfram alpha vs me. How did they get from what I had to what they had?

meager swanBOT
real gyro
#

I am sure this will help

lone star
#

If it was log instead of tan-1 that would make sense to me cos u can bring the power to the front but I didn’t know u could do that with tan-1

real gyro
#

New discovery club

#

I also got to know this now

#

On the internet

#

Fresh discovery for me too because of you

lone star
#

Is there a nice explanation for why that’s true

real gyro
#

Wait

lone star
#

Cos this doesn’t work and I don’t see how it’s just off by a constant cos that is not the same graph

real gyro
#

Hmm, I sure did see someone do it like this on the internet

#

Idk why

#

But see, I also do not have a correct explanation for this

lone star
#

Ah I see

real gyro
#

Still, u can treat it like a property

lone star
#

Well I’m not convinced it will hold for all powers

real gyro
#

Same

#

It did work for tan inv

lone star
#

And as the Desmos thing shows it doesn’t really seem true even with the ^-1

real gyro
#

Maybe it does not work for cos inverse

lone star
#

So it’s a bit confusing

real gyro
#

Cause cos returns positive value

#

For negative argument

#

We do need some advanced mathematicians for this problem

lone star
#

Yeah

#

Idk how to get advanced mathematicians to come here though 😂

#

It’s a huge server it’s hard to get noticed lol

waxen raft
#

Does that come from the fact that tan-1(x) + tan-1(1/x) = pi/2 ?

#

or -pi/2 but a constant anyway

real gyro
#

@lone star it's not a trigonometric identity it is just re-substituting $u=\mathrm{csec}, x$ in $\tan^{-1} u = \tan^{-1}(\mathrm{csec},x) $

#

or do you ask how one got $\int\frac{1}{1+u^2}\ \mathrm{d}u = \tan^{-1}u$ ?

reef pikeBOT
#

Landau08

#

Landau08

real gyro
#

(if you ask the latter, try the substitution $u=\tan v$ and use the identity $1 + \tan^2 = 1/\cos^2$ that can easily obtained from $\cos^2 + \sin^2 = 1$ when dividing by $\cos^2$)

reef pikeBOT
#

Landau08

lone star
lone star
lone star
lone star
#

Yeah

#

Found a nice explanation for why

real gyro
#

sorry, I first misunderstood the question,; above geometric proof is nice

lone star
#

No worries :)

waxen raft
# lone star So why is this true

You can simply derive and prove the derivative is 0, that is enough for your initial problem, you don't care about the value of the constant

lone star
#

.solved