Moir patterns, such as those shown in Exercises 6566, can appear when two repetitive patterns overlap to

Moiré patterns, such as those shown in Exercises 65–66, can appear when two repetitive patterns overlap to produce a third, sometimes unintended, pattern.

a. In each exercise, use the name of a conic section to describe the moiré pattern.

b. Select one of the following equations that can possibly describe a conic section within the moiré pattern: x² + y² = 1; x² - y² = 1; x² + 4y² = 4.