What is Arc length: Definition and 286 Discussions

Arc length is the distance between two points along a section of a curve.
Determining the length of an irregular arc segment is also called rectification of a curve. The advent of infinitesimal calculus led to a general formula that provides closed-form solutions in some cases.

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  1. V

    Find Arc Length of x = 1/3√y(y-3) 1 ≤ y ≤ 9

    Homework Statement find the length of the curve x = 1/3√y(y-3) 1 ≤ y ≤ 9 Homework Equations L = ∫ √(1 + (dx/dy)^2) The Attempt at a Solution x = 1/3√y(y-3) 1 ≤ y ≤ 9 x = 1/3 (y^3/2 - 3y^1/2) dx/dy = 1/2(y^1/2) - 1/2(y^-1/2) dx/dy = 1/2(y^1/2 -...
  2. MathWarrior

    Calc Arc Length 0 to 8, sqrt(1+x)

    Find the arc length of [PLAIN]http://www4d.wolframalpha.com/Calculate/MSP/MSP595419ebfac4cg3g1925000036iede4e50653655?MSPStoreType=image/gif&s=4&w=65&h=36 from 0 to 8Formula for Arc Length: integral from a to b of sqrt(1+[f(x)]^2) Attempt: f'(x) = 2/3 * 3/2 * x ^(1/2) f'(x) = x^(1/2) integral...
  3. 1

    Seemingly simple arc length problem I keep getting wrong

    Homework Statement Suppose you are headed toward a plateau 60 m high. If the angle of elevation to the top of the plateau is 25*, how far away from the plateau are you in meters? Homework Equations S = (theta)r The Attempt at a Solution In my head this translates as I am given...
  4. D

    Solving Arc Length of 9x^2 = 4y^2 from 0 to 1

    Homework Statement Homework Equations l = int( sqrt( 1 + (dy/dx)^2) dx) from a to b The Attempt at a Solution So far I'm stuck at the R^2 thing. I know if it was just R it would mean the set of all real numbers, but I'm not sure as to what R^2 means and I don't know how to google...
  5. Q

    Find Arc Length of Curve over [0, 2π]

    Homework Statement find arc length of curve over the interval t(0,2pi) r(t) = 10cos3t i + 10sin3t j The Attempt at a Solution i apply the formula integral ||r'(t)|| over the interval 0,2pi i get integrate sqrt((-30cos2tsint)2 + (30sin2tcost)2) and then finally get 15sin2t |0 to 2pi and i...
  6. M

    Arc Length of a Circle: Learn the Proof!

    Homework Statement Today we went over finding the arc length s of a circle with a given radian and radius... Thus s = radian*radius... Thats easy to remember but I think it will be more memorable for the long run if I knew the proof and understood it... can some one please post a website...
  7. C

    Arc Length Int. of r(t)=cos(t^2)+sin(t^2)+t^2 from 0 to sqrt(2pi)

    Homework Statement r(t)=cos(t^2)\hat{i}+sin(t^2)\hat{j}+t^2\hat{k} Compute the arc length integral from t=0 to t=\sqrt{2 \pi}Homework Equations Arclength = \int_{a}^{b}||v(t)||\, dtThe Attempt at a Solution I did the following: \\r'(t)=-2tsin(t^2)\hat{i}+2tcos(t^2)\hat{j}+2t\hat{k}\\...
  8. M

    Arc Length and Its Uses: Exploring the Integration Concept

    I always read in applications of integration is to figure out the arc length but they never tell us what is it good for I also couldn't find immediate results by using google, so can anyone tell me its uses?
  9. S

    Arc length of a circle using integration

    Hello there, suppose i want to find the arc length of a circle x^2+y^2=R^2 using integration, implicitly differentiating the equation, i find y'=-(x/y) now, arc length (circumference)= (\int \sqrt{1+y'^2}dx putting the value of y'=-(x/y) and substituting for y^2 from the equation of the...
  10. V

    Find the arc length of a polar function from 0 to 2pi

    Homework Statement This is another problem my teacher game me. Given the Polar function r=6*sin(t/2) where the variable t is the angle theta in radians, and that t is between 0 and 2*Pi inclusive. Find the distance around the perimeter of the graph. Hint: this is arc length , round to the...
  11. V

    The Arc length of a cable hanging from two poles x feet apart.

    Homework Statement I appologize if this is in the wrong topic. But, I need help with the. I know you guys don't exactly give out the answer, but I'm looking for a particular rule of something that will help me. My calculus professor told me to use any available resource to solve this problem...
  12. A

    Calculating Arc Length for a Polynomial Function on a Given Interval

    Homework Statement F(x) = (4/5)*x^(5/4) on the interval of [0,4] Find the Arc Length Homework Equations Arc Length = Integral (sqrt (1 + [f(x)']^2)) dx The Attempt at a Solution F'(x) = x^(1/4) Integral from [0,4] of Sqrt (1 + x^(1/2)) dx I'm not sure where to go with this...
  13. S

    How to Integrate sqrt(1+3x) Correctly?

    NVM bout the arc length, need help on integrations Homework Statement Integrate sqrt(1+3x)Homework Equations Sqrt (1+3x) The Attempt at a Solution i made it into (1+3x)^(1/2)
  14. B

    Polar Coordinates: Arc length of two overlapping curves

    This question may be something of a dumb one. I feel I should know this, but well, I don't. I'm being asked to find the perimeter inside of the curve r=15sin(theta) and outside of r = 1 Setting up the equation I can do. If it were just an indefinite integral, this would be cake. My...
  15. S

    Arc Length of Curve: Find Solution (-2,2) to (2,4)

    Homework Statement Find the arclength of the section y=x2 between points (-2,2) and (2,4) Homework Equations L = \int\sqrt{(\frac{dx}{dt})^2+(\frac{dy}{dt})^2}The Attempt at a Solution So what I did first is find the derivative of y=x2 which is y'=2x So I put that into the formula and get...
  16. C

    Calculating Distance Traveled (Arc Length)

    Homework Statement Given y = 156 - (x - 40)2/60. x = 0 and x = 85 Find distance traveled Homework Equations Arc Length S = integral of square root of ( y' )2 The Attempt at a Solution Doing this I get the trig sub tan(t) = (x - 40)/ 30 (Told by teacher to use this instead of...
  17. B

    Finding Function with Definite Integral & Arc Length

    Sorry, latex is being weird. I'm currently trying to come up with a way to find an equation that satisfies: s=\int_a^b \sqrt{(f'[x])^2+1} \, dx Which is arc length and G=\int_a^b f[x] \, dx which is area under the curve where A and s are known values, and f[a]=A, f[b]=B...
  18. D

    Getting the Arc Length Function

    Getting the "Arc Length Function" Homework Statement I have two problems scanned, one is an in class example and one is from the homework. The book uses the standard arc length of a curve equation to get the answers. Later in the same chapter they introduce the Arc Length Function, using 's'...
  19. L

    Calculating Arc Length for r(t)=(10t^2,2*sqrt(10)*t, ln t) from t=1 to t=8

    Homework Statement Find the arclength of the curve r(t)=(10t^2,2*sqrt(10)*t, ln t) for 1<=t<=8 Homework Equations The Attempt at a Solution i took the derivative of each component of vector r 20t,2sqrt(10),1/t then i square each term and square root it int sqrt( 400t + 40 +...
  20. R

    Approximating arc length of Bezier by another Bezier

    (Note: cross posted to http://www.devmaster.net/forums/showthread.php?t=16227 ) Hey everyone, As we know, the arc length of a cubic Bezier spline is kinda hard to calculate. There's no closed-form mathematical expression, so most people just subdivide it into a bunch of line segments and...
  21. Saladsamurai

    When is arc length ≈ chord length

    Homework Statement Maybe this is precalculus? Either way, here is a question that I am curious about. Take a circle of radius R and sweep out an arc length SAB with endpoints 'A' and 'B' over angle theta. For a short enough arc length, I believe that we could approximate SAB by the chord...
  22. C

    Calculating Arc Length for f(x) = 4/5*X^5/4 from [0,4]: Step-by-Step Guide

    I need to find the arc length of the function f(x) = 4/5*X5/4 from [0,4]. You have to find f '(x) first and that would be X1/4 I square f '(x) and obtain X1/2 or \sqrt{X} I plug it into the formula and get S = \int\sqrt{1+\sqrt{X}} from [0,4] I don't know how to evaluate the...
  23. K

    How Do You Find an Arc Length Parametrization for a Given Curve?

    Homework Statement Find an arc length parametrization of the curve r(t) = <e^t(cos t), -e^t(sin t)>, 0 =< t =< pi/2, which has the same orientation and has r(0) as a reference point. Homework Equations s = int[0,t] (||r'(t)||) The Attempt at a Solution So I found the derivative of r(t), and...
  24. S

    How Do You Calculate the Length of a Cardioid in the First Quadrant?

    Homework Statement Find the length of the cardioid with equation r = 1 + cos (theta) located in the first quadrant Homework Equations f (theta) = 1 + cos (theta) f'(theta) = -sin (theta) s = antiderivative (0 to (pi/2)) sq rt (f(theta)^(2) + f'(theta)^(2)) d(theta) The Attempt at...
  25. S

    Calculating Arc Length for Polar Curve r = theta^(2)

    Homework Statement Find the length of r = theta^(2) for 0<=theta<=pi Homework Equations Arc length s = antiderivative of sq rt (f (theta)^(2) + f (derivative theta)^(2)) The Attempt at a Solution I have worked my way to the antiderivative of sq rt (theta^(4) + 4(theta)^(2)) but I'm...
  26. P

    Arc Length in Polar Coordinates

    In the polar formula for arc length, ds^{2}=dr^{2}+r^{2}d{\theta}^{2}, what is the exact meaning of the r^2 term multiplying d{\theta}^2? Is it an initial distance from the origin? A final distance from the origin? The change in r from point a to point b? This baffles me to no end and nothing...
  27. H

    Arc length of vector function curve

    Homework Statement 1. Find the length of the curve from t=0 to t=1. r(t) = <2t, t^2, (1/3)t^3> 2. Reparametrize the curve with respect to arc length measured from the point where t=0 in the direction of increasing t. r(t) = <e^(2t)cos2t, 2, e^(2t)sin2t>Homework Equations S = \int{r'(t)} dt...
  28. K

    Concept: Arc Length Parametrization

    What does the arc length parametrization mean?
  29. B

    Find the arc length of f(x) (x^(5/4))/5

    Homework Statement find the arc length of f(x) (x^(5/4))/5. The integration limits are from 0 to 4. Homework Equations The arc length formula is integrate sqrt(1 + (f'(x))^2) The Attempt at a Solution f'(x) = (5/4)*(1/5)*x^(1/4) = x^(1/4)/4 integral of sqrt(1 +...
  30. S

    Polar Regions: Area, Arc Length, and Surface Area

    Homework Statement Consider the graph (see attachment) of r = 1 +2cos\Theta in polar coordinates. SET UP integrals to find 1. the area inside the large loop minus the area of the small loop. 2. the arc length of the small loop 3. the surface area of the surface formed by...
  31. L

    Area, Arc Length, Volume & Curved Area of y=√x

    Homework Statement For the curve y=\sqrt{x} , between x = 0and x = 2, find (a) the area under the curve, (b) the arc length, (c) the volume of the solid generated when the area is revolved about the x axis, (d) the curved area of this solid. Homework Equations ds = \sqrt {1+(y')^{2}}dx...
  32. J

    Finding the Arc Length of a Polar Function

    Hi, I've been having some issues in solving this problem. Homework Statement Find the arc length of r=2/(1-cosθ) from π/2 to πHomework Equations L =(integrate) sqrt(r2+(dr/dθ)2)dθ The Attempt at a Solution I found (dr/dθ) = (-2sinθ)/(1-cosθ)2 so (dr/dθ)2 = (4sin2θ)/(1-cosθ)4 Then r2 =...
  33. R

    Define Circle Knowing Two Points and ARC LENGTH Only.

    I am having trouble doing exactly what the title says. I have two points and the arc length between them (this is a bending beam type of a situation). Essentially I know where the ends of the beam are and how long the bent beam is and I need to get the equation of the circle. And yes I...
  34. K

    Finding Arc Length when given velocity and launch angle

    Homework Statement Find the arc length of the projectile from launch until the time it hits the ground, given that 0 V is 100 feet/sec and is 45 degrees. Homework Equations Arc Length= ∫_a^b▒√(█(1+(f^' (x) )^2@)) dx Arc Length of Curve= ∫_a^b▒〖v(t)dt=∫_a^b▒√((dx/dt)^2+(dy/dt) )〗^2...
  35. R

    Solving for arc length of an ellipse

    Homework Statement The task is to solve for the arc length of an ellipse numerically. a & b are given for an ellipse centered at the origin and a value for x is given. Homework Equations Equation of ellipse is given to be x^{2}/a^{2} + y^{2}/b^{2} = 1 and the equation to solve for the arc...
  36. O

    Arc Length of e^5x from 0 to ln(4)

    Homework Statement http://i47.tinypic.com/1z6naa.jpg Note... I used wolfram alpha to get the answer, I did not get it myself... So I still need help. The answer shown is correct, so you'll know if you got it. Homework Equations Integral [0, ln(4)] sqrt(1+(dy/dx)^2) The Attempt at a...
  37. 3

    Solving Arc Length Problem: y=x^5/6+1/10x^3, 1≤x≤2

    Homework Statement Find the arc length of the curve: y=\frac{x^5}{6}+\frac{1}{10x^3} 1\leqx\leq2 Homework Equations ds=\sqrt{dx^2+dy^2} ds=\sqrt{1+\frac{dy}{dx}^2}dx The Attempt at a Solution \frac{dy}{dx}=\frac{5}{6}x^4-\frac{3}{10x^4}...
  38. S

    Arc length: Can't Solve the Integral

    Find the exact length of the curve analytically by antidifferentiation: y = (x3/3) + x2 + x + (1/(4x +4)) on the interval 0 < x < 2So I set it up using the length of a curve formula: L = \int\sqrt{1+(x^2+2x+1+(\frac{-1}{4(x+1)^2}} And simplified it to L =...
  39. M

    Arc Length of y=ln((e^(x)+1)/(e^(x)-1))

    Arc length of y=ln((e^(x)+1)/(e^(x)-1)) on [a,b] Using L=\int\sqrt{1+(y')^2}dx on [a,b] I am having difficulties differentiating y and plugging the results back into get a useful integral. So far I have y'=2e^(x)/(e^(2x)-1)
  40. Y

    Calc III Problem Integrating Sq Rt's in Arc Length Formula

    Hey guys, I'm studying for a test in calc 3 tomorrow and have run into a problem. On the practice test we have a problem "Find the length of the curve: r=theta^2, 0≤theta≤pi/2" I know the length of a curve in polar coordinates is int(sqrt(r^2 + (dr/dtheta)^2))dtheta...but when I get to where...
  41. C

    Line integral with respect to arc length

    In a line integral with respect to arc length, we have something like f(x, y)ds "inside" the integral sign. The ds tells us that we are working with the arc length function s, taking diferences (s_K+1 - s_k) in the sums that tend to the line integral. Question: do we shall understand that...
  42. C

    When we use arc length as a parameter

    If we have a fly in a room, its position respect to some frame of reference will change with time, so if we want to describe the fly's movement with a parametrized curve, it is easy to see the convenience of taking time as the parameter. I read that we can also take the length of the curve as...
  43. Char. Limit

    Arc Length Confusion: What is the Idea Behind it?

    Why is arc length of a function f(x) from a to b defined as \int_a^b \sqrt{1+(f'(x))^2} dx? Where they get the idea of squaring the derivative, adding 1, taking the square root, and then integrating it is beyond me.
  44. O

    How do i generalize this result to higher dimensions? (arc length, surface area)

    a derivation of the formula for arc length is simple enough: given a function f[x], find the length of the arc from x0 to x1. lim(x1-x0)/n=dx n->inf x1 S=^{i=n-1}_{i=0}\sum\sqrt{(x+(i+1)dx-(x+idx))^2+f(x+(i+1)dx)-f(x+dx))^2} xo...
  45. L

    Topological Definition of Arc Length

    In calculus, the definition of the arc length of some curve C is the limit of the sum of the lengths of finitely many line segments which approximate C. This is a perfectly valid approach to calculating arc length and obviously it will allow you calculate correctly the length of any...
  46. O

    How do i find the arc length of an implicit curve given by f[x,y]=0?

    ? i used the implicit function theorem to find dy/dx, then applied that to the arc length formula, but i have to integrate with respect to x and there is the implicit function y[x] inside the radical. also, if it matters, the curve is assumed to be closed.
  47. S

    Arc length of vector function with trigonometric components

    Homework Statement Find the length of the path traced out by a particle moving on a curve according to the given equation during the time interval specified in each case. r(t) = (c2/a)cos3t i + (c2/b)sin3t j where i and j are the usual unit vectors, 0 \leq t \leq 2\pi, c2 = a2 - b2, and 0...
  48. 2

    Arc Length Problem: Find s & Deduce y=e-s | Oscar

    Hey guys, Got a bit of a problem with a question I found in a textbook. I can do most of it but there's one little part I'm really struggling with: A curve C is given parametrically by: x=t-tanht, y=secht, t\geq0 The length of arc C measured from the point (0,1) to a general point...
  49. M

    Find Arc Length of r(t): Solving Homework Problem

    Homework Statement Find the arc length of r(t)= <10sqrt(2), e^10t, e^-10t>, 0 <_ t <_ 1. <_ is greater than or equal to. Homework Equations arc length= integral(magnitude of the derivative of r(t)) The Attempt at a Solution i thought I figured the answer out and got an arc...
  50. R

    Calculating Arc Length of a Vector Function

    Homework Statement Find Arc Length: r(t)=t^3 i+tj+(1/2)\sqrt{6}t^2k 1\leqt\leq3Homework Equations The arc length formula: integrate: sqrt((dx/dt)^2+(dy/dt)^2+(dz/dt)^2) dtThe Attempt at a Solution I can find the derivative and plug into the formula, it's just the simplification that is...
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