Final answer:
An angle is defined by the union of two rays with a common endpoint. Rays are significant in mathematical concepts especially in geometric optics where they describe how light travels and the behavior of light regarding lenses and mirrors.
Step-by-step explanation:
Angle is a union of two rays with a common endpoint. In mathematics, this configuration is when two straight lines that originate from the same starting point (the vertex of the angle) spread out in different directions. Each individual line is referred to as a ray, and together, they create what is known as an angle.
The concept of a ray is significant in various areas of mathematics and science, including geometric optics. In optics, for example, the concept of rays is used to describe the path of light as it travels through different mediums, and understanding the behavior of rays is crucial in analyzing phenomena such as the focal point of lenses and mirrors.