Answer: The roots are \(x=\sin\left(\frac{7\pi}{30}\right),\sin\left(\frac{11\pi}{30}\right),\sin\left(\frac{31\pi}{30}\right),\sin\left(\frac{35\pi}{30}\right),\sin\left(\frac{43\pi}{30}\right)\).
Let \(z=\cos\theta+i\sin\theta\). Then by de Moivre's theorem,
\(z^5=(\cos\theta+i\sin\theta)^5=\cos 5\theta+i\sin 5\theta\).
Expanding the left-hand side and taking imaginary parts gives
\(\sin 5\theta=5\cos^4\theta\sin\theta-10\cos^2\theta\sin^3\theta+\sin^5\theta\).
Now write \(\cos^2\theta=1-\sin^2\theta\). Then
\(\sin 5\theta=5\sin\theta(1-\sin^2\theta)^2-10\sin^3\theta(1-\sin^2\theta)+\sin^5\theta\).
Expanding and simplifying:
\(\sin 5\theta=5\sin\theta(1-2\sin^2\theta+\sin^4\theta)-10\sin^3\theta+10\sin^5\theta+\sin^5\theta\)
\(=5\sin\theta-10\sin^3\theta+5\sin^5\theta-10\sin^3\theta+10\sin^5\theta+\sin^5\theta\)
\(=16\sin^5\theta-20\sin^3\theta+5\sin\theta\).
So \(\sin 5\theta=16\sin^5\theta-20\sin^3\theta+5\sin\theta\), as required.
Now let \(x=\sin\theta\). The equation
\(32x^5-40x^3+10x+1=0\)
can be written as
\(2(16x^5-20x^3+5x)+1=0\),
so using the identity just proved,
\(2\sin 5\theta+1=0\).
Hence \(\sin 5\theta=-\frac12\).
Now solve \(\sin u=-\frac12\). In \([0,2\pi)\), the solutions are
\(u=\frac{7\pi}{6},\frac{11\pi}{6}\).
So for \(u=5\theta\),
\(5\theta=\frac{7\pi}{6},\frac{11\pi}{6},\frac{19\pi}{6},\frac{23\pi}{6},\frac{31\pi}{6}\)
giving
\(\theta=\frac{7\pi}{30},\frac{11\pi}{30},\frac{19\pi}{30},\frac{23\pi}{30},\frac{31\pi}{30}\).
Therefore the roots, in the form \(\sin(q\pi)\), are
\(\sin\left(\frac{7\pi}{30}\right),\sin\left(\frac{11\pi}{30}\right),\sin\left(\frac{19\pi}{30}\right),\sin\left(\frac{23\pi}{30}\right),\sin\left(\frac{31\pi}{30}\right)\).