>> Do you know how to count how much beer's left in a can?

'Cause if you look inside, you can't say how to estimate it from outside, right?

>> Right.

>> That's it. So I'm gonna tell you how to make it possible.

>> How?

>> You peep into the can and slope it, so beer level touches the corner of your can.

From the outside you can easily lead a horizontal line from that corner to the opposite edge of the can.

Then you mark the point of the edge's and the line's intersection with your finger

And you calculate the lenght of the segment between your can's bottom and your finger.

And yet, from Pythagorean theorem you calculate the lenght of hypotenuse of triangle

that consist of can's bottom's diameter, the segment between can's bottom and the finger

and the segment between the finger and the other corner, the one which abuts on beer level.

After all, it's not necessary, because if you know the lenghts of can's bottom's diameter,

the segment between the finger and the other corner,

that is the second short side, you can calculate the area of the triangle.

So you make an equation: the area of the triangle equals the area of the rectangle which consists

of two diameters of the can's bottom and the true beer level,

I mean the beer level when we stand the can upright.

And the only unknown of this equation is the real beer level.

So we calculate the equation and we get what we look for.

>> You are stupid.