Euler's Machin-Like Formula

The Machin-Like Formula

$${\textstyle{1\over 4}}\pi=\tan^{-1}({\textstyle{1\over 2}})+\tan^{-1}({\textstyle{1\over 3}}).$$

The other 2-term Machin-Like Formulas are Hermann's Formula, Hutton's Formula, and Machin's Formula.

See also Inverse Tangent