An instrument used for setting out right angle in surveying a parcel of land is?

An instrument used for setting out a right angle in surveying a parcel of land is an optical square. An optical square is a type of surveying instrument that is used to determine right angles and ensure that measurements are accurate. It consists of a small telescope that is mounted at a 90-degree angle to a sighting device. The optical square is used in surveying to establish right angles, align structures, and set out corners and boundaries of a parcel of land. By using an optical square, surveyors can ensure that the measurements they take are accurate and that the boundaries of the parcel of land are set out correctly.