The other 2-term Machin-like formulas are Hermann's formula, hutton's formula, and Machin's formula.
Euler's Machin-Like Formula
See also
Hermann's Formula, Hutton's Formula, Inverse Tangent, Machin's Formula, Machin-Like FormulasExplore with Wolfram|Alpha
References
Borwein, J. and Bailey, D. Mathematics by Experiment: Plausible Reasoning in the 21st Century. Wellesley, MA: A K Peters, p. 105, 2003.Referenced on Wolfram|Alpha
Euler's Machin-Like FormulaCite this as:
Weisstein, Eric W. "Euler's Machin-Like Formula." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/EulersMachin-LikeFormula.html