Curves Definition and 741 Threads

  1. T

    Trying to find the area between two curves

    A circle with radius 1 touches the curve y = |2x| in two places(see attachment for picture). Find the area of the region that lies between the curves. I am having a tough time with this one. I figured I could put the radius in a spot where it would form a right angle on the line, then try...
  2. P

    Hyperbolic Geometry: Parameterization of Curves for Hyperbolic Distance

    Homework Statement Consider the points P = (1/2, √3/2) and Q = (1,1). They lie on the half circle of radius one centered at (1,0). a) Use the deifnition and properites of the hyperbolic distance (and length) to compute dH(P,Q). b) Compute the coordinates of the images of Pa nd Q...
  3. D

    Find tangent lines to both curves

    Homework Statement Find the equation of all straight lines, if any, that are tangent to both the curves y = {x^2} + 4x + 1 and y = - {x^2} + 4x - 1.Homework Equations The Attempt at a Solution Suppose such a line exists and its slope is m. Let ({x_1},{y_1}) and ({x_2},{y_2}) be the tangent...
  4. M

    Tangents to Curves: Intersection in First Quadrant

    Homework Statement Is there anything special about the tangents to the curves xy=1 and (x^2) - (y^2) =1 at their point of intersection in the first quadrant. The Attempt at a Solution I know what the derivatives of both functions are and what they look like when graphed. But, I'm not...
  5. D

    Finding ODE for Family of Orthogonal Curves to Circle F

    Homework Statement Consider the family F of circles in the xy-plane (x-c)2+y2=c2 that are tangent to the y-axis at the origin. What is a differential equation that is satisfied by the family of curves orthogonal to F? Homework Equations ∇f(x,y)=<fx,fy> The Attempt at a SolutionMy general...
  6. M

    Find the area between three curves

    Homework Statement Sketch the region enclosed by the curves and compute its area as an integral along the x or y axis. y+x=4 y-x=0 y+3x=2 Homework Equations [SIZE="6"]∫ top function - bottom function dx OR [SIZE="6"]∫ right function-left function dy The Attempt at a Solution...
  7. N

    What are the methods for transforming rotated conic sections to standard form?

    I am trying to find the level curves for the function g(x,y)= k = xy/(x^2+y^2). I get, x^2+y^2-xy/k=0. I know this is an ellipse, but I do not know how to factor, and find values of k for which the level curves exist.
  8. S

    Given value of a line integral, find line integral along different curves

    Given value of a line integral, find line integral along "different" curves Homework Statement I think I've got this figured out, so I'm just checking my answers: Suppose that \int_\gamma \vec{F}(\vec{r}) \cdot d\vec{r} = 17 , where \gamma is the oriented curve \vec{r}(t) = \cos{t} \vec{i}...
  9. D

    Why Does the Area Between Curves in Terms of y Seem Negative?

    Hello, I have a question regarding finding the area between two curves. I will link to a well known example that seems to show up in every calculus textbook! http://tutorial.math.lamar.edu/Classes/CalcI/AreaBetweenCurves.aspx In particular on that page, I am referencing Example 6. And in...
  10. G

    Need Guidance: Area in between Polar Curves

    Homework Statement Find the area of the region that lies inside both of the circles r = 2sin(x) r = sin(x) + cos(x) Homework Equations A = (1/2)(int from a to b): r^2 dx (I apologize because I do not know how to make calculus look proper in text form) The Attempt at a Solution...
  11. mnb96

    How to obtain a 2D-coordinate system from two family of curves?

    Hello, it is known that if we have a curvilinear coordinate system in ℝ2 like x=x(u,v), y=y(u,v), and we keep one coordinate fixed, say v=\lambda , we obtain a family of one-dimensional curves C_{\lambda}(u)=\left( x(u,\lambda),y(u,\lambda) \right). The analogous argument holds for the other...
  12. A

    Timelike Curves leads to violation of heisenberg uncertainty Relation

    General Relatitivity predicts Timelike curves and there are nonlinear extensions of mechanics which resolve the paradoxical aspects of CTC's *i.e. Time Travel, on the other hand Hawking proposed a conjeture to rule out CTCs, the Chronology Protection Conjecture* there are a class of Timelike...
  13. L

    How to compute the level curves of this function

    Homework Statement I have this function of two variables: f(x,y)=x^2-4x+y^2 Where I have to compute the level curves for: f(x,y)=-3, -2, -1, 0, 1 Homework Equations - The Attempt at a Solution So yeah well I know that I have to draw the following curves...
  14. B

    Bezier Curves in Mechanical Design

    Hi Folks, Sorry if this has been asked before but I have searched the forums and can't anything to do with this. Also please correct me if I am posting in the wrong forum. I am making an application with functionality similar to a revolution of a sketch within any CAD program. I...
  15. P

    Plot IV Curves for Solar Panels Easily

    hi Guys, can anyone suggest me some software by which i can plot IV curve for solar panels by just feeding in open circuit voltage, short circuit current, max power, max current and voltage, efficiency.
  16. T

    Analyzing surfaces and curves using Implicit Function Thm

    for each of the following maps f: ℝ2-->ℝ3, describe the surface S = f(ℝ2) and find a description of S as the locus of an equation F(x,y,z) = 0. Find the points where \partialuf and \partialvf are linearly dependent and describe the singularities of S(if any) at these points f(u,v) = (2u + v...
  17. K

    Area of Polar Curves: Find & Calculate with Step-by-Step Guide

    1. Given the curves r = 2sin(θ) and r = 2sin(2θ), 0≤θ≤π/2, find the area of the region outside the first curve and inside the second curve 2.not sure which equations to use 3. I got 1 and 1/2 as the area and they were wrong. I do not really know how to work this problem. A...
  18. E

    Study materials about Closed timelike curves (CTCs)

    I'm looking for some study materials regarding Closed time-like curves (CTCs). Be it a book, paper or anything other. It is highly accepted, but I'm particularly looking for a book that includes it and similar topics.
  19. P

    Calculating Area Between Two Curves

    Find the area of the region bounded by the following curves: y=x2-5x and y=3-x2 Answer: So, using simultaneous equations I found the points of intersection (x = -0.5 and x = 3). The book agrees with me on that. I then performed the following: 3-x2-(x2-5x) = -2x2+5x+3 I then...
  20. H

    Find the COG of two cubic curves

    The first part of the question asks to find the COG of the curve y=[1-x]*x^2 in the interval x=0 to x=1 I found that correctly as (0.6,0.0571) The next part asks to find the COG of another cubic curve y=x[1-x]^2 But without using integration but by using the result of the first part of...
  21. D

    Calculus area between two curves

    Homework Statement How to Find the area of ​​the shaded region in the image below: http://i47.tinypic.com/263ed5d.jpg (without space)Hi, please help me with this: How to find the common points in between the curves? and the area?? Homework Equations y= x^2 y= (x-2)^(1/2) x = 0 The...
  22. C

    Area of a region between two curves

    Homework Statement Set up sums of integrals that can be used to find the area of the region bounded by the graphs of the equations by integrating with respect to y. y= sqrt(x) y=-x x=1 x=4 Homework Equations ∫[f(x) - g(x)] dxThe Attempt at a Solution I did: ∫ (from 1 to 4) [sqrt(x) + x] dx...
  23. I

    Integrating Areas between curves

    I can't figure how to solve this problem. Is says ∫∫(x^2)y dA where R is the region bounded by curves y=(x^2)+x and y=(x^2)-x and y=2. I can't figure how to do the limits with that. Please help!
  24. C

    Sketching level curves and the surface of a sphere

    Homework Statement (a) Sketch the level curves of z = (x^2 - 2y +6)/(3x^2 + y) at heights z = 0 and z =1. (b) Sketch the surface (x−1)^2 + (y+2)^2 + z^2 = 2 in R^3. Write down a point which is on the surface. Homework Equations -- The Attempt at a Solution (a) From the question, I...
  25. R

    Sketch Level Curves for z=0 and z=1: Tips and Tricks for Accurate Plotting

    sketch the level curve z=(x^2-2y+6)/(3x^2+y) at heights z=0 and z=1 i have already compute the 2 equations for the 2 z values and drawn it in 2d but when it comes to plotting it with the extra z axis i don't know what to do. please help...
  26. A

    Approximating Areas Under Curves

    Good morning! I'm having a bit of a hard time wrapping my mind around this concept. The part that seems to be troubling me the most is where Riemann Sums and sigma notation come in. I can't seem to find explanations online that help me better understand, so hopefully someone here could help...
  27. B

    Finding the area between two curves

    Homework Statement find the area enclosed by the two curves y=x+1 y=x^2-3x-4 i've already worked out the points of intersection. these are x=-1 and 5 what do i do now? and how? i'd appreciate if you could tell me because i have loads of these to do, so one good example would...
  28. S

    Integrating Polar Curves over Period

    Hello. I am having trouble conceptualizing and/or decisively arriving to a conclusion to this question. When finding the area enclosed by a closed polar curve, can't you just integrate over the period over the function, for example: 3 cos (3θ), you would integrate from 0 to 2pi/3? It intuitively...
  29. V

    Limits of integration for regions between polar curves

    Alright. I completely confused about determining the area between regions of polar curves. However, I do feel that I have a solid grasp in finding areas for single functions. For a given function in polar form, I know that I find the limits of integration by setting the function equal to zero...
  30. G

    Plank curves and emission/absorbtion spectra

    i understand that a good black body would produce a plank curve. it is my understanding that plank curves are continuous emmision spectra.. now the sun a good approximation to a black body... but we get and emission/absorbtion spectra.. can you please help me understand where i am going...
  31. Math Amateur

    Area of a Triangle and Elliptic Curves - Birch and Swinnerton Dyer Conjecture

    In the book by Keith Devlin on the Millenium Problems - in Chapter 6 on the Birch and Swinnerton-Dyer Conjecture we find the following text: "It is a fairly straightforward piece of algebraic reasoning to show that there is a right triangle with rational sides having an area d if and only if...
  32. J

    Friction Force on Banked Curves

    Homework Statement A car weighing 3220 lbs rounds a curve a 200 ft radius banked at an angle of 30deg. Find the friction force acting on the tires when the car is traveling at 60mph. Coefficient of friction is 0.9. Homework Equations i rotated the axes such that y-axis is...
  33. J

    Figuring Out Function from Curve: Is it Possible?

    Given a function, it is easy enough to plot its curve, just by substituting numerical values. But is the reverse possible? I mean, if you're given a curve's figure, can you figure out the function that represents it (provided that the curve is not a well-known one like a parabola or ellipse) ?
  34. D

    Mathematica Plotting phase curves Mathematica

    I was talking to my professor and I am tying to generate a phase curve that looks like (see attached).However, I am only been able to generate phase portraits.I need to generate a plot that does that.From these equations,$$\dot{x} = -x + ay +x^2y$$$$\dot{y} = b -ay-x^2y$$Here is what I have been...
  35. T

    Nonsensical (lack of) relation between area and arc-length of polar curves

    It is known that the area of a sector of a polar curve is \frac{1}{2}\int r^{2} d \theta This of course comes from the method of finding the area of an arc geometrically, by multiplying the area of the circle by the fraction we want \frac{\theta}{2\pi}\pi r^{2} Today I learned how...
  36. S

    Area between Curves: Find Area Enclosed by y=x-1 and y^2=2x+6

    Homework Statement Find the area enclosed by the line y = x-1 and the parabola y^2 = 2x+6 The Attempt at a Solution This is Example 6 in Jame's Stewart Calculus Early Transcentals 6E. I'm trying to figure out why he states that if we were to integrate with respect to x instead of y...
  37. M

    Vector calculus, normals to plane curves

    Homework Statement show that n(t)=-g'(t)i+f'(t)j and -n(t)=g'(t)i-f'(t)j are both normal to the curve r(t)=f(t)i+g(t)j at the point (f(t),g(t)). Homework Equations The Attempt at a Solution i tried finding the unit normal of r(t) in hopes that it would be exactly what n(t) and...
  38. M

    Homotopic Jordan curves in C [pic included]

    This isn't homework but I'm having trouble understanding the concept of non-homotopic and homotopic Jordan curves. My understanding of Jordan curves and homotopy: A Jordan curve is a simple closed curve (ie a closed curve that only intersects at the endpoints; f(z1)=f(z2) => z1=z2) such that...
  39. A

    Drawing curves in Spherical coordinate

    I had a tutorial today and my tutor said these questions are very trivial so we can simply look at it at home. But after going home, I found that I don't know how to do Q 35. I know that p<3 is responsible for the big sphere with r=3. But I don't know why the other part is responsible for...
  40. Barnak

    Mathematica truncates my curves

    I'm ploting a simple function (the effective gravitationnal potentiel with angular momentum part) with Mathematica, and I'm getting some truncated curves close to the vertical asymptote located at r = 0 (see the picture below). Of course, this is normal since the function V(r) diverges at r =...
  41. W

    Classification of events and curves in Minkowskian spacetime

    I'm trying to understand the causal structure of Minkowskian spacetime and I was wondering whether something can be said about the relation between the classification of events and curves. To clarify: for Minkowskian inner product \eta with signature (-+++), two events p and q can be timelike...
  42. P

    Closed Curves on the Riemann Sphere

    Is the imaginary axis considered a closed curve on the Riemann Sphere?
  43. C

    Help with isotherms and adiabatic curves

    This is to help me understand a problem in the book, I don't want to state the question I'm attempting to solve though I would rather just get a nudge in the right direction conceptually. (I am analyzing an isotherm and adiabatic curve at the same point.) My book states that for an ideal gas...
  44. A

    Banked curves, coefficient of friction problem

    Homework Statement A road with a radius of 74.8 m is banked so that a car can navigate the curve at a speed of 15 m/s without any friction. When a car is going 21.1 m/s on this curve, what minimum coefficient of static friction is needed if the car is to navigate the curve without slipping...
  45. J

    Finding area between 2 curves with 3 intersections

    Homework Statement I need help getting the area between 2*x^3-x^2-5*x and -x^2+2*x. I found the intersections at +/- sqrt(7/2) and 0. Homework Equations f(x)=2*x^3-x^2-5*x g(x)=-x^2+2*x The Attempt at a Solution This is the problem, I know that for something simple like x^2 and...
  46. S

    Friction & Curves: Direction & Explanation

    Homework Statement If a car goes around a curve, which direction is its friction? Pointed towards the circle or outwards? Explain please. Thanks in advance. Homework Equations The Attempt at a Solution
  47. B

    How Do Parametric Curves and u-Substitution Relate to Length Calculation?

    Homework Statement x = t^3, y = (3t^2)/2 0<= t <= √3 The Attempt at a Solution dx/dt = 3t^2 dy/dt = 3t step 1. √((3t^2)^2 + (3t)^2) step 2. 3t^2 + 3t (the book says I can't do that, I don't see why) step 3. insert √3 into t Here's the books solution I...
  48. fluidistic

    Solving Exact Diff. Eq: Finding Integral Curves

    Homework Statement Find the solution to y'=\frac{y+x}{y-x} and graph the integral curves.Homework Equations Exact differential equation.The Attempt at a Solution I noticed it's an exact differential equation, I solved it implicitely. I reached that \frac{y^2...
  49. ElijahRockers

    Angle of intersection between two parametric curves

    Homework Statement This is a problem involving parametric equations. r1= <t,2-t,12+t2> r2= <6-s,s-4,s2> At what point do the curves intersect? Find the angle of intersection, to the nearest degree. The Attempt at a Solution I found the point of intersection, (2,0,16). This is when t=2 and...
  50. J

    Area Between Two Curves (Sin and Cos)

    Homework Statement Sketch the regions enclosed by the given curves. And determine the area between the curves. y = 7 cos 3x, y = 7 sin 6x, x = 0, x = π/6 Homework Equations The Attempt at a Solution Okay so i ended up solving the question, because i used the help of my graphing calculator...
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