$\arctan (x) + \arctan(1/x) = \frac{\pi}{2}$
59658
Are $\mathrm{arccot}(x)$ and $\arctan(1/x)$ the same function?
10289
Need help in proving that $\frac{\sin\theta - \cos\theta + 1}{\sin\theta + \cos\theta - 1} = \frac 1{\sec\theta - \tan\theta}$
19561
Why is $\frac{1}{\frac{1}{X}}=X$?
82170
Solve $x = \frac{1}{2}\tan(x)$
2676
Finding $\frac {d(\tan \theta)}{d\theta}$
65562
Proving the inequality $\arctan\frac{\pi}{2}\ge1$
48956
Simplify $\arctan (\frac{1}{2}\tan (2A)) + \arctan (\cot (A)) + \arctan (\cot ^{3}(A)) $
85872
Prove $1 + \tan^2\theta = \sec^2\theta$
42391
Calculate $\tan9^{\circ}-\tan27^{\circ}-\tan63^{\circ}+\tan81^{\circ}$
24234
How to evaluate $\lim_{x\to\infty}\arctan (4/x)/ |\arcsin (-3/x)|$?
2491
For $0 < x < \pi/2 $, prove that $x + \frac{x^{3}}{3} <\tan x $
17769
Show that $\frac{\sin x}{\cos 3x}+\frac{\sin 3x}{\cos 9x}+\frac{\sin 9x}{\cos 27x} = \frac{1}{2}\left(\tan 27x-\tan x\right)$
2411
Integrate $\int_0^{\pi/2} \frac{1}{1+\tan^\alpha{x}}\,\mathrm{d}x$
75679
How to prove that $2 \arctan\sqrt{x} = \arcsin \frac{x-1}{x+1} + \frac{\pi}{2}$
69803
An elementary proof of $\int_{0}^{1}\frac{\arctan x}{\sqrt{x(1-x^2)}}\,dx = \frac{1}{32}\sqrt{2\pi}\,\Gamma\left(\tfrac{1}{4}\right)^2$
33905
Prove the following trigonometric identity: $\frac{\tan A+\sec A-1}{\tan A-\sec A+1}=\frac{1+\sin A}{\cos A}$
104453
A question about the arctangent addition formula.