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 Calculus Calculus Math Forum

 February 20th, 2017, 04:03 AM #1 Newbie   Joined: Feb 2017 From: Norway Posts: 3 Thanks: 0 Curve Hi! I got some problems understanding this math task, so would appreciate all help I could get!: Task: Let σ(t) be the curve σ(t) = cos(t)i + sin(t)j, and put r(t) = e^(-t) *σ(t). a) Sketch the curve r(t) for t ∈ [0, 4π] b) Find the lenght of the segment r(t) for t ∈ [0, ∞) c) Show that r(t) satisfies this differential equation:  February 21st, 2017, 04:46 AM #2 Math Team   Joined: Jan 2015 From: Alabama Posts: 3,264 Thanks: 902 Have you not even attempted this? You are given that and . Calculate a number of (x, y) values and plot them. If you are really lazy, you can use the graphing program at https://www.desmos.com/calculator. Enter (e^(-t)cos(t), e^(-t)sin(t)) as the function to be graphed. If a curve is given as parametric functions, x= f(t), y= g(t), then the arc length, from to is given by . What do you get for that integral? I cannot see the differential equation it is supposed to satisfy. Did you try just finding the derivatives and putting them into the equation? Tags curve Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Similar Threads Thread Thread Starter Forum Replies Last Post oliver92 Applied Math 1 November 21st, 2015 03:43 AM Azzajazz Calculus 4 September 16th, 2015 05:21 PM jiasyuen Calculus 1 April 14th, 2015 06:57 AM mared Calculus 2 June 20th, 2014 07:22 PM Marin Advanced Statistics 0 March 30th, 2009 01:23 PM

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