What is the arclength of (t^2lnt,(lnt)^2)(t2lnt,(lnt)2) on t in [1,2]t[1,2]?

1 Answer
Nov 16, 2016

I used Wolframalpha to evaluate the integral.

L = 2.815L=2.815

Explanation:

Here is a reference for Arc length of parametric equations

From the reference, the equation for arclength is:

L = int_alpha^beta sqrt((dx/dt)^2 + (dy/dt)^2)dtL=βα(dxdt)2+(dydt)2dt

dx/dt = (d[t^2ln(t)])/dt = 2tln(t) + tdxdt=d[t2ln(t)]dt=2tln(t)+t

dy/dt = (d[(ln(t))^2])/dt = (2ln(t))/tdydt=d[(ln(t))2]dt=2ln(t)t

I used Wolframalpha to evaluate the integral:

L = int_1^2 sqrt((2tln(t) + t)^2 + ((2ln(t))/t)^2)dt = 2.815L=21(2tln(t)+t)2+(2ln(t)t)2dt=2.815