In geometry, for any line segment AB and angle $\theta < \pi$, the locus of points $C$ on one side of line $AB$ such that angle $ACB$ equals θ is an arc of a circle. Points outside this arc form sharper angles than $\theta$, while points within this arc form wider angles.
In the Swiss school curriculum this arc is known as an "Ortsbogen" and the theorem that the locus has this shape is known as the Ortsbogen theorem.
https://en-academic.com/dic.nsf/enwiki/10100669
What is the name of this arc in English?