Back to parabolas...
Remember the parabolas we saw before? In bridges... and paths of projectiles like when you throw a ball in the air.
They have cool reflective properties too.
Check it out:
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This is why paraboloids are used as satellite dishes and as the mirrors in telescopes.
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And check out these flood lights:
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Can you see from the reflective properties who paraboloids would make great flood lights? (Compare this to the ellipsoidal spot lights.)