Given that radius is r= 4.1 inches.
let track the location of finger hole is at 12 o'clock.
i.e. the angle is 0 degree.
at 12 o'clock
[tex]\theta=0[/tex]Now when the finger hole changed by 45 degree:
[tex]\theta=45[/tex]Now convert 45 degree into radians:
[tex]\begin{gathered} \theta=45\times\frac{\pi}{180} \\ \theta=\frac{\pi}{4} \end{gathered}[/tex]So angle is such that:
[tex]\begin{gathered} \theta\in\lbrack0,\frac{\pi}{4}\rbrack \\ 0\leq\theta\leq\frac{\pi}{4} \end{gathered}[/tex]Now calculate the measure of function in polar coordinates:
[tex]\begin{gathered} \theta=0,\text{ f(}\theta\text{)}=r \\ \theta=\frac{\pi}{2},\text{ f(}\theta)=r\cos \theta \end{gathered}[/tex]Taking measurement of function:
[tex]\begin{gathered} f(\theta)=r+r\cos \theta \\ f(\theta)=r(1+\cos \theta) \end{gathered}[/tex]So the function become and the limit is:
[tex]f(\theta)=r(1+\cos \theta),\text{ 0}\leq\theta\leq\frac{\pi}{4}[/tex]