Solution:
The arc length when angle in radians is given by formula:
[tex]s = r \times \theta[/tex]
Where,
r is the radius
From given,
[tex]r = 4.5\\\\s = \frac{9 \pi }{8}[/tex]
Substituting the values we get,
[tex]\frac{9 \pi }{8} = 4.5 \times \theta\\\\\theta = \frac{9 \pi }{8 \times 4.5}\\\\\theta = 0.25 \pi[/tex]
Thus angle of a sector of a circle is or [tex]0.25 \pi[/tex] or 0.785 radians
