- #1
Electrophy6
- 18
- 0
Homework Statement
[/B]
Show that the given parametric curve decribed by the following notations:
x=cos(t), y=sin(t), z=2+2cos(t)
lies in a single plane ,find the normal vector to this plane
Homework Equations
---[/B]
r(t)=cos(t) i + sin(t) j + 2+2cos(t) k
The Attempt at a Solution
My attempt was finding the osculating plane to this parametric curve using the follwing equations
Tangent(t)=(r'(t)/|r'(t)|) ===> Normal(t)=(T'(t)/|T'(t)|)
Binomial=T X B
[/B]
I tried this method , yet it takes a much longer time than I guess required for solving this question---and actually I was told there is a simple way to solve this problem ...
Another attempt was trying to isolate t and substituing it in 'z' and 'y' ...Yet it doesn't help me any way
my general idea is actually proving the normal vector points the same direction in every point on the curve
---------------------------------------------------------------------------------------------------------
I would like to mention ,someone who solved a simillar problem on another forum used the formula
Normal vector to the plane = (r' x r'')/ |r' x r''|.
Yet I couldn't find this formula or any proof of it in any of Calculus textbooks(Stewart,Thomas,Anton...) -and in class we have never encountered this formula -so we are not allowed to use it...(BTW ,in which textbook can I find this formula and its proof?)
-------------------------------------------------------------------------------------------------------------Thank you!