Visualizing a Parametric Equation in 3D Space

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The discussion centers around visualizing the parametric equation x=2, y=sin(t), z=cos(t) in 3D space. One participant concludes that the equation describes a sphere with a radius of √5, based on the derived equation x²+y²+z²=5. However, another participant argues that since x is always equal to 2, the shape should be a circle rather than a sphere. The confusion arises from the interpretation of the equation, with the suggestion that there is only one degree of freedom (t), indicating a line rather than a surface. Ultimately, the participants are debating the geometric representation of the given parametric equation.
CourtneyS
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Homework Statement


Given the eqn x=2, y=sin(t), z=cos(t), draw this function in 3-space.

Homework Equations


ABOVE^

The Attempt at a Solution


I did this:
x^2+y^2+z^2=2^2+(sin(t))^2+(cos(t))^2=5
Therefore we get x^2+y^2+z^2=5
Which is the eqn of a sphere with radius root5.

My friend said it's supposed to be a circle but I can't see how?
Which one of us is right if either.
 
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If x is always equal to 2, how can it be a sphere?
 
phyzguy said:
If x is always equal to 2, how can it be a sphere?
:(
 
CourtneyS said:
:(
Another way of looking at it... there is only one degree of freedom (t), so it must be a line, not a surface.
 
Question: A clock's minute hand has length 4 and its hour hand has length 3. What is the distance between the tips at the moment when it is increasing most rapidly?(Putnam Exam Question) Answer: Making assumption that both the hands moves at constant angular velocities, the answer is ## \sqrt{7} .## But don't you think this assumption is somewhat doubtful and wrong?

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