Let c be parametrized by x = et sin (10t) and y = et cos (10t) for 0 ≤ t ≤ 2. find the length l of
c. l = 2 correct: your answer is correct.

Respuesta :

[tex]C:x(t)=e^t\sin10t;\,y(t)=e^t\cos10t;\,0\le t\le2[/tex]

[tex]\displaystyle\int_0^2\sqrt{x'(t)^2+y'(t)^2}\,\mathrm dt[/tex]
[tex]\displaystyle=\int_0^2\sqrt{(e^t\sin10t+10e^t\cos10t)^2+(e^t\cos10t-10e^t\sin10t)^2}\,\mathrm dt[/tex]
[tex]\displaystyle=\int_0^2e^t\sqrt{\sin^210t+20\sin10t\cos10t+100\cos^210t+\cos^210t-20\sin10t\cos10t+100\sin^210t}\,\mathrm dt[/tex]
[tex]=\displaystyle\int_0^2e^t\sqrt{1+100}\,\mathrm dt[/tex]
[tex]=\displaystyle\sqrt{101}(e^2-1)[/tex]