So, what's the deal with conic sections?
All the shapes we'll be talking about in this chapter are slices out of a cone.
If you slice a cone horizontally, you get a circle:
What makes a circle a circle?
Geometrically, that is... Yes, I know circles are round, but, let's get a little more specific.
|Check out this animation:
A line segment of a set length
A little more technically, all those red points on the circle are the same distance from the green center point.
What if you took a long rope and a board or plank... Can you think of a way to make a crop circle?
Check out this link: CircleMakers.org
Yeah, circles are cool things -- you see them everywhere. But, spheres are really where it's at!
Slices of spheres are used for all sorts of lenses in optics.
|This Fresnel lamp uses slices of spheres
to help aim light.
Here are some links where you can see spheres in action: