[color=#000000]What not-well-known trigonometric identity is dynamically being illustrated here without words?[br](Hint: It involves the inverse tangent function!) [/color]
[color=#000000][b]Trigonometric Identity: [/b][/color][br][br][math]tan^{-1}\left(1\right)+tan^{-1}\left(2\right)+tan^{-1}\left(3\right)=\pi[/math]