The Student Room Group
Reply 1
The answer is arctan(x) + C
Reply 2
substitute x=tanθx = \tan \theta
Reply 3
kabbers
substitute x=tanθx = \tan \theta


How did you just "know" that?
Reply 4
aster100
How did you just "know" that?


experience.. it is also done to death in FP2 :p:
You are looking for a trig function such that 1+(something)^2 will give you a single function. So in this case, u=tanθu=tan\theta or cotθcot\theta will work because 1+tan2θ=sec2θ1+tan^2\theta= sec^2\theta, and similar for
Unparseable latex formula:

cot\thet

.
You could also try a hyperbolic function such as sinhθsinh\theta.
Reply 6
Well I knew the standard result. I wasn't sure, until just now, how you thought up such an efficient substitution.
aster100
Well I knew the standard result. I wasn't sure, until just now, how you thought up such an efficient substitution.


Dont know if you seen my post above?
It's obvious, but strangely, never pointed out in my book anyway. Works especially well for square roots.
Reply 8
silent ninja
Dont know if you seen my post above?
It's obvious, but strangely, never pointed out in my book anyway. Works especially well for square roots.


nice

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