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#math
<arctanx> correct to there
<arctanx> depends on your domain for t
<slxAlex> same as before
<slxAlex> probably be (pi)/4, -(pi)/4
<slxAlex> right?
<arctanx> -pi <= t <= pi, then that's not right
<arctanx> as 7pi/4 is > pi
<slxAlex> but -(pi)/4?
<slxAlex> that's the same
<slxAlex> same angle
<arctanx> yep
<arctanx> that one's fine
<arctanx> yes you're right pi/4, -pi/4
<slxAlex> can you tell me what answers I should get
<arctanx> that's it
<arctanx> t = +- pi/4
<slxAlex> book not agree
<arctanx> % Reduce[2*Cos[t]^2 == 1, t]
<mbot> arctanx: C[1] \[Element] Integers && (t == (-3*Pi)/4 + 2*Pi*C[1] || t == (3*Pi)/4 + 2*Pi*C[1] || t == -Pi/4 + 2*Pi*C[1] || t == Pi/4 + 2*Pi*C[1])
<slxAlex> it says t also = +- 3(pi)/4
<arctanx> as does this
<slxAlex> so why is that?
<arctanx> oh I know
<slxAlex> it can't lie there because cos is positive
<arctanx> you have to remember to take both positive and negative square root
<arctanx> so Cos(t) = 1/sqrt(2) and Cos(t) = 1/-sqrt(2)
<slxAlex> ahhh
<slxAlex> right
<arctanx> my bad
<slxAlex> no no
<slxAlex> you very good
<slxAlex> arctanx++
<arctanx> nah I always forget those, should learn one of these days
<arctanx> anyway, you happy now?
<slxAlex> well
<slxAlex> a little more happier than I was an hour ago
<yaarg> slxAlex: good luck btw!
<slxAlex> lol cheers
<yaarg> :)
<NonSatiation> Hi If I'm asked to give the series for e^(x^2) not from first principles but from standards results...
<NonSatiation> how would i go about doing it?
<yaarg> e^x = 1 + x/1! + x^2/2! + x^3/3! + .....
<asphyxia> Hi, I seem to have lost my memory. I am given this assignment: Let f be a differential map IR^3 -> IR. Determine the derivative of t -> f(t,t^2,e^t).
<asphyxia> How should I derive that?
<asphyxia> f(1,2t,e^t)?
<asphyxia> Or is it f
<asphyxia> oh
<NonSatiation> yaarg: yeah and how do I get E^(x^2) from that?
<asphyxia> is it f'x(t,2t,e^t) + 2t f'y(t,2t,e^t) + e^t f'z(t,2t,e^t) ?
<asphyxia> anyone?
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