- The radian is a unit which connects the radius of an arc, the length of the arc and the angle subtended by the arc.
- In other words, when two plates subtended the same angle - one big and far away, the other small and nearby - the antennae also made the same angle with each other.
- Reticles are in the second focal plane, so as power is changed the angle subtended by the space between lines varies.
- The space between the dot and the first letter of the prime to the right of fixation subtended a visual angle of 21.
- The most common geometry for curved crystal diffraction is based on the Rowland circle principle, which relies on the well-known property of a circle that an arc segment subtends a constant angle for any point on the circle.