Just remember, you're going 1 over 4A below the vertex.

Conic by Directrix, Focus Point

Construct a conic with this point as focus

Select the focus of the new conic...

Focal length

Focal

Focal Length

Focal blur

Focal point

First Focus

Second Focus

Focal Length

Focal length

And this is f2.

And it's for focus.

Focal length of the lens

Well, we just used the distance formula.

Or they can be, I don't want to say always.

A conic with given directrix and focus, through a point

We have focused on the worst case scenario.

That's our directrix and it has the equation y is equal to k.

There is an equation that governs all of this, and it looks about as follows

And what we want to do is, we want to find out the coordinates of the focal points.

We now care about the baseline B, if we happen to know the object is 100 meters away.

Ellipse by Focuses Point

35mm equivalent focal length

That's this distance right there.

And that's what we set out to figure out in the beginning.

And you enter that space, and you feel like, Wow!

Requires great focus.

Just focus.

Bifocals.

Your focus,

Hyperbola by Focuses Point

I'll call that well, we'll call that a focus because it will be a focus.

But where's the focus point?

So you know that a is equal to x1.

So let's solve for the focal length.

Focal Length

Telescope focal length

Eyepiece focal length

So let's call that a directrix.

An object at range of 100 meters

And you essentially divide 1 by 4 times this value.

Well, the first thing you do is though I've never well, we could just figure out the focal length just by plugging into the formula.