Orthoptic of a closed Fermat curve
Orthoptic of the Fermat curve of degree 6
The closed Fermat curve F_n has equation x^n+y^n=1, for n even. It si convex and smooth. Therefore it has isoptic curves for any angle theta (a theta-isoptic curve of F_n is the geometric locus of points from which F_n is viewed under the angle theta).
A general study of isoptics of closed Fermat curves is to appear in "Mathematics and Computer Science" (a paper by Th. D-P, A. Naiman, W. Mozgawa and W. Cieslak.
Orthoptic of the Fermat curve of degree 6
The closed Fermat curve F_n has equation x^n+y^n=1, for n even. It si convex and smooth. Therefore it has isoptic curves for any angle theta (a theta-isoptic curve of F_n is the geometric locus of points from which F_n is viewed under the angle theta).
A general study of isoptics of closed Fermat curves is to appear in "Mathematics and Computer Science" (a paper by Th. D-P, A. Naiman, W. Mozgawa and W. Cieslak. https://doi.org/10.1007/s11786-019-00419-2