been having trouble getting results in CAS system
01-22-2018, 08:02 AM
Post: #3
 webmasterpdx Senior Member Posts: 541 Joined: Sep 2015
RE: been having trouble getting results in CAS system
Parisse,
Ah, I didn't realize, we already have an arcLen() function.
So, I can use arcLen(y(x),x,a,b)
Of course, you are right....it's not easy to calculate using this format....is the same math internally.

So, if I set z:=1, n:=3, a:=0, b:=1

y = (1-x^3)^(1/3)

dy/dx = -x^2/((1-x^3)^(1/3))^2

(1+(dy/dx)^2)^(1/2) = ((-x^2/((1-x^3)^(1/3))^2)^2+1)^(1/2)

So, now, we can calculate int((1+(dy/dx)^2)^(1/2),x,0,1) like this, and it'll give a value of 1.

However int(((-x^2/((1-x^3)^(1/3))^2)^2+1)^(1/2),x,0,1) hangs for a minute and gives an answer of an integral...i.e. doesn't get solved.

Why does it work with dy/dx but not with the expanded form????
Thanks
-Donald
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 Messages In This Thread been having trouble getting results in CAS system - webmasterpdx - 01-21-2018, 09:19 AM RE: been having trouble getting results in CAS system - parisse - 01-22-2018, 07:03 AM RE: been having trouble getting results in CAS system - webmasterpdx - 01-22-2018 08:02 AM RE: been having trouble getting results in CAS system - webmasterpdx - 01-22-2018, 09:39 AM RE: been having trouble getting results in CAS system - parisse - 01-22-2018, 08:04 PM RE: been having trouble getting results in CAS system - webmasterpdx - 01-24-2018, 09:02 AM RE: been having trouble getting results in CAS system - parisse - 01-24-2018, 03:22 PM

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