SOLUTION
Given the question on the question tab;
[tex]\begin{gathered} radius\text{ r=0.9} \\ angle\text{ }\theta=? \\ Length\text{ of arc=3.6} \end{gathered}[/tex][tex]\begin{gathered} Length\text{ of arc =}\theta r \\ 3.6=0.9\theta \\ \theta=\frac{3.6}{0.9} \\ \theta=4.0 \end{gathered}[/tex]
The angle is 4.0