- In geometry, a tridecagon or triskaidecagon or 13-gon is a thirteen-sided polygon.
- Compass (Wikipedia)
A compass is a device that shows the cardinal directions used for navigation and geographic orientation. It commonly consists of a magnetized needle or other element, such as a compass card or compass rose, which can pivot to align itself with magnetic north. Other methods may be used, including gyroscopes, magnetometers, and GPS receivers.
