Lee help (1 Viewer)

[umm what]

I am sorry I cnt upload the pic.

Terry Lee Advanced Mathematics : CHapter 6 (page 132)
Example 6.1

how the side length of the equilateral triangle is 2y?

THANKS !

 

[billym]

If you look at the diagram on page 132 notice that the z-axis is usually where you would expect the y-axis to be.

Look "from above" at the x-y plane and you can see that the base of the triangle stretches from the top of the parabola, to the x-axis (a distance of y), then to the bottom of the parabola (a distance of y).

So the side length of the triangle is 2y.

 

[umm what]

If you look at the diagram on page 132 notice that the z-axis is usually where you would expect the y-axis to be.

Look "from above" at the x-y plane and you can see that the base of the triangle stretches from the top of the parabola, to the x-axis (a distance of y), then to the bottom of the parabola (a distance of y).

So the side length of the triangle is 2y.

I don't get the second bit :S

 

[billym]

Look at the parabola in the x-y plane (note that it is a parabola on its side). Say that the point (x, y) lies on this parabola, then the point directly below (x, y) that lies on the parabola is (x, -y).

The distance between these two points is 2y, and this is the side length of the triangle.

 

[umm what]

I am sorry, my teacher has not started this topic yet so I can't ask her.

Look at the parabola in the x-y plane (note that it is a parabola on its side). Say that the point (x, y) lies on this parabola, then the point directly below (x, y) that lies on the parabola is (x, -y).

The distance between these two points is 2y, and this is the side length of the triangle.

Can you like mark the points how it 2y....coz i dun get this 3D diagram

 

[billym]

 

[billym]

What it would look like looking from above (note same colours represent same features as diagram above):

 

[Carrotsticks]

What it would look like looking from above (note same colours represent same features as diagram above):
View attachment 25128

Very nice diagram! What programs did you use? Looks like Microsoft Word and... ??

 

[billym]

Using a mac, graphed the parabola on Autograph then took a screenshot and pasted it into keynote (basically powerpoint for mac).

 

[umm what]

Now I get it, thanks a lot man!!!!!

What it would look like looking from above (note same colours represent same features as diagram above):
View attachment 25128