# What is Tangent vector: Definition and 55 Discussions

For a more general — but much more technical — treatment of tangent vectors, see tangent space.In mathematics, a tangent vector is a vector that is tangent to a curve or surface at a given point. Tangent vectors are described in the differential geometry of curves in the context of curves in Rn. More generally, tangent vectors are elements of a tangent space of a differentiable manifold. Tangent vectors can also be described in terms of germs. Formally, a tangent vector at the point

x

{\displaystyle x}
is a linear derivation of the algebra defined by the set of germs at

x

{\displaystyle x}
.

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10. ### Tangent vector on the intersection of surfaces

Homework Statement The surfaces ##x^2+y^2 = 2## and ##y=z## intersect in a curve ##C##. Find a unit tangent vector to the curve ##C## at the point ##(1,1,1)##. Homework EquationsThe Attempt at a Solution So I'm thinking that we can parametrize the surfaces to get a vector for the curve ##C##...
11. ### Angle between vector and tangent vector

Homework Statement My problem is: For the logarithmic spiral R(t) = (e^t cost, e^t sint), show that the angle between R(t) and the tangent vector at R(t) is independent of t. Homework Equations N/A The Attempt at a Solution The tangent vector is just the vector that you get when you take the...
12. ### Unit tangent vector of r(t) = (e^t)(cos t ) i + (e^t)(sin t

Homework Statement Find the unit tangent vector T(t) for vector valued function r(t) = (e^t)(cos t ) i + (e^t)(sin t ) j + (e^t) k Homework EquationsThe Attempt at a Solution i gt stucked here ... , the ans is [1/ sqrt (3) ] [ (cos t -sin t ) i + (sin t + cos t ) j +k) [/B]
13. ### I Velocity with respect to arclength is a unit tangent vector?

Hi all, I have long had this unsolved question about arclength parameterization in my head and I just can't bend my head around it. I seem not to be able to understand why velocity with arclength as the parameter is automatically a unit tangent vector. My professor proved in class that s(s) =...
14. ### Unit tangent vector vs principal normal vector

Homework Statement http://mathwiki.ucdavis.edu/Core/Calculus/Vector_Calculus/Vector-Valued_Functions_and_Motion_in_Space/The_Unit_Tangent_and_the_Unit_Normal_Vectors In the link, I can't understand that why the Principal Unit Normal Vector is defined by N(t) = T'(t) / | T'(t) | ,can someone...
15. ### I Question about a Tangent Vector

In the following book, please look at equation 3.16. Why are the components of the tangent vector given by ui = dxi/dt? I understand the velocity components would be dxi/dt and the velocity vector would be a tangent vector. Is that the same reasoning the author uses? The book is normally crystal...
16. ### Rotations in differential geometry

Simple and basic question(maybe not). How are rotations performed in differential geometry ? What does the rotation matrix look like in differential geometry? Let us assume we have orthogonal set of basis vectors initially. I am looking to calculate the angle between two geodesics. Can this...
17. ### Differential geometry : Tangent vector & reparameterization

Homework Statement Problem statement uploaded as image. Homework Equations Arc-length function The Attempt at a Solution Tangent vector: r=-sinh(t), cosh(t), 3 Now, I just need to reparameterize it using arclength and verify my work is unit-speed. Will someone give me a hint? Should I use...
18. ### Tangent spaces at different points on a manifold

Why are tangent spaces on a general manifold associated to single points on the manifold? I've heard that it has to do with not being able to subtract/ add one point from/to another on a manifold (ignoring the concept of a connection at the moment), but I'm not sure I fully understand this - is...
19. ### Equation of the tangent line in the direction of a vector

I am having issues figuring out how to do the "in the direction of the vector" part of my problem I have found the equation of the tangent line but i do not know how to the the next part. My question asks: Find the equation of the tangent line to the surface defined by the function f(x,y) =...
20. ### Unit Tangent Vector in a Scalar Field

Hello, I am attempting to calculate unit normal and tangent vectors for a scalar field I have, Φ(x,y). For my unit normal, I simply used: \hat{n}=\frac{\nabla \phi}{|\nabla \phi|} However, I'm struggling with using this approach to calculate the unit tangent. I need to express it in terms of the...
21. ### Evaluate the partial derivative of a matrix element

Homework Statement A determinant a is defined in the following manner ar * Ak = Σns=1 ars Aks = δkr a , where a=det(aij), ar , Ak , are rows of the coefficient matrix and cofactor matrix respectively. The second term in the equation is the expansion over the columns of both matrices, δkr is...
22. ### Tangent vector as derivation question

I have a question concerning the tangent space. Consider a manifold Mn and take Mn to be ℝn with the Euclidean metric for the purposes of this question. The directional derivative of a function in the direction of a vector v is (a) vf = ∑ vi(∂f/∂xi) where the sum runs from 1 to n. The...
23. ### Tangent Vector for r=sint, theta=t/3

Homework Statement Find the tangent vector and unit tangent vector for the curve: r=sint, theta=t/3 for 0<=t<=6pi. Homework Equations If the tangent vector is r'(t)e(hat)r + r*theta(t)e(hat)theta, how does the restriction on t affect the answer? The same for the unit tangent vector, they don't...
24. ### Tangent vector to curve - notational confusion.

Given a curve ##\gamma: I \to M## where ##I\subset \mathbb{R}## and ##M## is a manifold, the tangent vector to the curve at ##\gamma(0) = p \in M## is defined in some modern differential geomtery texts to be the differential operator $$V_{\gamma(0)}= \gamma_* \left(\frac{d}{dt}\right)_{t=0}.$$...
25. ### Finding a curve's unit tangent vector

Homework Statement Homework Equations I know the equations. See question below. The Attempt at a Solution I am just wondering with this problem, how is it that they go from that derivative to the magnitude at the bottom of that image? I know the formula, but what I mean is...
26. ### MHB Find Tangent Vector & Vector Equation for Curve r(t)

For the curve defined by r(t) = 3*t*i + 2*t^2*j − 3*t^4*k Find the tangent vector r′(t0) at the point P(4,8,−16), given that the position vector of P is r(t0). and Find the vector equation of the tangent line to the trajectory through P. Im unsure as to how to go about solving this. I've...
27. ### How is the Chain Rule Applied in Geometric Tangent Vectors?

So let ℝ^{n}_{a}={(a,v) : a \in ℝ^{n}, v \in ℝ^{n}} so any geometric tangent vector, which is an element of ℝ^{n}_{a} yields a map Dv|af = Dvf(a) = \frac{d}{dt}|_{t=0}f(a+tv) this operation is linear over ℝ and satisfies the product rule Dv|a(fg) = f(a)Dvg + g(a)Dvf if v|a =...
28. ### MHB Unit tangent vector and equation of tangent line to curve

"find a unit tangent vector and the equation of the tangent line to the curve r(t) = (t, t^2, cost), t>=0 at the point r(pi/2)." NOW, what I don't get is, how is that a curve? This is not like the example I have studied and I don't really get the question. So I don't know where to start. Once I...
29. ### Exploring the Relationship Between the Chain Rule and Tangent Vectors

Homework Statement Show that: \frac{dx^\nu}{d \lambda} \partial_\nu \frac{dx^\mu}{d \lambda} = \frac{d^2 x^\mu}{d \lambda^2} The Attempt at a Solution Well, I could simply cancel the dx^nu and get the desired result; that I do understand. But what about actually looking at...
30. ### Tangent vector to a parametric curve

This is confusing me more than it should. A curve in space is given by x^i(t) and is parameterized by t. What is the tangent vector along the curve at a point t= t_0 on the curve?
31. ### Problem involving tangent vector, normal vector, binormal vector and curvature

Homework Statement r(t)=cos(t)i+sin(t)j+sin(2t)k Find the curvature κ, the unit tangent vector T, the principal normal vector N and the binormal vector B at t=0. Find the tangential and normal components of the acceleration at t=∏/4 Homework Equations T(t)=r'(t)/|r'(t)| N(t)=T'(t)/|T't|...
32. ### Given the plane curve, find tangent vector

Homework Statement Consider the plane curve \overrightarrow{r(t)}=e^tcost(t)\hat{i}+e^tsin(t) \hat{j} Find the following when t= ∏/2 Part A: \hat{T}(t) Part B: \hat{B}(t) Part C: \hat{N}(t) Homework Equations \hat{N}(t)=\frac{\hat{T}(t)}{||\hat{T}(t)||}...
33. ### Integral of unit tangent vector equals arc length?

Homework Statement Let c(t) be a path and T the unit tangent vector. What is \int_c \mathbf{T} \cdot d\mathbf{s} Homework Equations The unit tangent vector of c(t) is c'(t) over the magnitude of c'(t) : \mathbf{T} = \frac{c'(t)}{||c'(t)||} The length of c(t) can be represented by ...
34. ### Find unit tangent vector at indicated point

Homework Statement Find the unit tangent vector at the indicated point of the vector function r(t) = e(19t)costi + e(19t)sintj + e(19t) kT(pi/2) = <___i+___j+___k>Homework Equations r'(t) / |r'(t)| The Attempt at a SolutionAnswers: 19e(19*∏/2)(cos(∏/2)-sin(∏/2)) /...
35. ### Tangent vector to a curve (Differential geometry/Lie theory).

Homework Statement Let c(s) = \left( \begin{array}{ccc} \cos(s) & -\sin(s) & 0 \\ \sin(s) & \cos(s) & 0 \\ 0 & 0 & 1 \end{array} \right) be a curve in SO(3). Find the tangent vector to this curve at I_3 . Homework Equations Presumably, the definition of a tangent vector as a differential...
36. ### Finding a vector given a tangent vector

Homework Statement Find a tangent vector r that satisfies r(0)= (e^(1),0) given T(t) = (-e^(cos(t)sin(t)),cos(t)), where t is an element of [0,2π] Homework Equations Tangent vector T = r'(t)/(norm(r'(t)) The Attempt at a Solution I was thinking that r(t) = ∫r'(t), and that the norm of r(t)...
37. ### Unit Tangent Vector of a curve / Arc Length

Homework Statement Find the curve's unit tangent vector. Also, find the length of the indicated portion of the curve. Homework Equations r(t) = (-3tcost)i + (3tsint)j + (2\sqrt{2})t(3/2)k 0 ≤ t ≤ ∏ The Attempt at a Solution So I found dr/dt (I think), which is v(t) =...
38. ### Finding the Tangent Vector at a Point

I can use the tangent vector and a point.
39. ### Position vector perpendicular to tangent vector yields a sphere

Homework Statement If a curve has the property that the position vector r(t) is always perpendicular to the tangent vector r'(t), show that the curve lies on a sphere with center the origin. Homework Equations -1/r'(t)= slope of position vector x^{2}+y^{2}=1 The Attempt at a...
40. ### What determines the magnitude of a tangent vector?

The unit tangent vector, T(t) = r'(t) / || r'(t) || always has length 1. Alright, so how do we get a sense of the length of the actual tangent vector itself? Its direction is easy to imagine, but I can't understand how its magnitude changes along the curve (does it have something to do with...
41. ### Finding a tangent vector to the intersection of two surfaces

Homework Statement The surfaces S1 : z = x2 + y2 and S2 : x2 + y2 = 2x + 2y intersect at a curve gamma . Find a tangent vector to at the point (0, 2, 4). Homework Equations i thought about finding gradients of the two functions and plug in the given point in the gradients and cross...
42. ### Finding the Tangent Vector of a Space Curve at a Given Point

Homework Statement Here's a worked problem, I can't understand how they have evaluated T at the given point (in part c): [PLAIN]http://img31.imageshack.us/img31/3725/97856984.gif The Attempt at a Solution I just substituted (0,1, \pi/2) into r'(s) but \frac{1}{\sqrt{2}} cos...
43. ### Something about tangent vector

hey there, i got stuck on an question here: Parameterise the following paths, in the dirction stated, and hence find a tagent vector(in the same dirction) to each point on the paths. (a)The upper part of the circled centred at (0,0) containing the points (-2,0) and (2,0) going anticlockwise...
44. ### Solve Unit Tangent Vector at Point P: Find T, N, B

Homework Statement Find the vectors T, N, and B at the given point. r(t) = (sin(t), cos(t), ln(cos(t))), P = (0,1,0) Homework Equations T(t) = r'(t) / | r'(t) | N(t) = T'(t) / | T'(t) | B(t) = T(t) x N(t) The Attempt at a Solution I am stuck on how to solve for t. I am not...
45. ### Tangent vector to curve of intersection of 2 surfaces

Homework Statement Find the tangent vector at the point (1, 1, 2) to the curve of intersection of the surfaces z = x2 + y2 and z = x + y. Homework Equations The Attempt at a Solution I haven't started the problem, because I'm not sure what the first thing to do is. Do I have to parametrize...
46. ### Hard time visualizing gradient vector vs. tangent vector.

OK, this is really confusing me. Mostly because i suck at spatial stuff. If the gradient vector at a given point points in the direction in which a function is increasing, then how can it be perpendicular to the tangent plane at that point? If it's perpendicular to the tangent plane...
47. ### Unit tangent vector to a curve at a point

Homework Statement Find the unit tangent vector T(t) to the curve r(t) at the point with the given value of the parameter, t. r(t)=<e^(2t), t^(-2), 1/(3t)> t=1 Homework Equations none The Attempt at a Solution So first I took the derevative to get r'(t) which I got to be...
48. ### Position vector and tangent vector in Riemannian spaces

In Euclidean vector spaces the derivative of the position vector of a running point of a curve is the tangent vector of the curve. In thehttp://www.matematik.lu.se/matematiklu/personal/sigma/Riemann.pdf" , on page 78 appears a vector which can be regarded as position vector in a Riemann space...
49. ### Curvature in terms of the tangent vector

My teacher wrote an alternative equation on the board for curvature, and I am wondering how it is true: k = | dT/dt / |dR/dt| | where T is the unit tangent vector. I know k = |R' x R''| / |R'|^3 = |dT/ds| but I am not sure about the formula in question. How is it true/derived?
50. ### Unit Tangent Vector at a Point

Homework Statement r(t) = costi + 2 sint j Find the tangent vector r'(t) and the corresponding unit tangent vector u(t) at point P:(.5, 3.5,0) Homework Equations r'(t) = r(t)dt u(t) = r'(t) / |r'(t)| The Attempt at a Solution r'(t) = -sinti + 2costj |r'(t)| = [sin2t +...