As [Huygens Optics] explains, mirrors ground to each of these shapes have different properties, which makes it hard to build telescopes that work at astronomical and terrestrial distances.

A 2D shape is symmetrical if a line can be drawn through it and either side is a reflection of the other. The line is called a line of symmetry. This is sometimes called a 'mirror line' or 'mirror ...

Here’s what they say I should keep in mind: Size and shape: Before buying a mirror, it’s important to define what you plan to use the mirror for so that you can find an option with the right ...