Show that [tex]\arctan{x} + \arctan {y} = \arctan { \frac{x+y}{1-xy} }[/tex] when [tex]x = \frac{1}{2}\ and \y = \frac{1}{3}[/tex] but not when [tex]x = 2\ and \y = 3[/tex](adsbygoogle = window.adsbygoogle || []).push({});

I've tried taking the tangent of both sides but I don't know what to do then when I've got [tex]\tan ( \arctan{x} + \arctan{y} ) = \frac{x+y}{1-xy}[/tex]

Any help would be greatly appreciated. Thanks!

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# Inverse tangent proof

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