Designed to be mathematically necessary?
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Design and Mathematics are inseperable when it comes to satellites and satellite dishes. Satellite dishes have a parabolic shape. It's a shape with surfaces that reflect towards a focus point inside of the shape. At this point, most satellite dishes have a receiver to collect the information being received. It's designed this way so that the greatest amount of information being sent to the dish is collected.
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Another example of parabolas being used in design is headlights. The surfaces are made out of a reflective material that focuses away from the light bulb. The light bulb represents the focus as mentioned in the examples with the satellites. The parabolas allow the light to be more focused and shoot straight ahead. It's the same with flashlights. That's why your flashlight doesn't just shoot light out in every direction like when you turn on a lamp.