- #1
MxwllsPersuasns
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Homework Statement
Let γ : I → ℝ2 be a smooth regular planar curve and assume 0 ∈ I. Take t ≠ 0 in I such that also −t ∈ I and consider the unique circle C(t) (which could also be a line) containing the 3 points γ(0), γ(−t), γ(t). Show that the curvature of C(t) converges to the curvature κ(0) of γ at t = 0 when t → 0. This also shows that the curvature is a geometric quantity, i.e. parametrization invariant
Homework Equations
κ = det{γ',γ''}/{absval(γ')}3
The Attempt at a Solution
Like the previous 2 problems I've posted about tonight I'm unsure whether this should be done in general (taking γ to be as general a representation of a smooth regular planar curve (whatever that may be) as possible) or if I should be specific (i.e., parameterize γ by t, perhaps like an ellipse <acos(t), bsin(t)>.
I'm not sure where to start exactly if it's the general case but I would imagine I would take C(t) to be a circle? (parameterized like gamma is but with a=b) then find the curvature at each point and then also find the curvature of the curve at t = 0 then take the limit of the curvature of C(t) as t approaches 0 and try to show they are equivalent?
If anyone can help me either conceptually on whether I can do this problem through a specific example or rather if it needs be proven in a more abstract way ( and how one does that) or in a procedural sense, or in other words if my method seems to be on the right track. Thanks in advance for anyone who can offer me any help. This homework is due on friday so I'll be on much of the day tomorrow (Feb 10th) to answer anyone who responded. Thanks again!