Mass of a wire in shape of helix
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syms x y z r t rho
x=cos(t*pi)
y=sin(t*pi)
z=8*t
r=[x,y,z]
rho=x^2+y^2+z^2
int(rho*norm(diff(r,t)),t,[0,1])
cos^2(x)+sin^2(x) should be equal to 1. As the problem above it not simply to 1. What are the way to simplify the answer by cos^2(pi*t)+sin^2(pi*t)= 1.
Answers (1)
Bjorn Gustavsson
on 14 Jun 2022
The symbolic tools make the default interpretation that all variables are complex. Therefore it cannot make that simplification.
If you explicitly constrain the variables to be real and use the simplify suggestion by@Ganesh you get:
syms x y z r t rho real
x=cos(t*pi)
y=sin(t*pi)
z=8*t
r=[x,y,z]
rho=x^2+y^2+z^2
Lengthofhelix = simplify(int(rho*norm(diff(r,t)),t,[0,1]))
HTH
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