I don't understand this.
So we have:
\begin{align} r &= 12 \color{gray}{\text{ (radius of circle)}} \\ d &= 24 \text{ (r}\times2) \color{gray}{\text{ (diameter of circle)}} \\ c &= 24\pi \text{ (}\pi\times d) \color{gray}{\text{ (circumference of circle)}} \\ a &= 144\pi \text{ (}\pi\times r^2) \color{gray}{\text{ (area of circle)}} \end{align}
And we have:
\begin{align} ca &= 60^\circ \color{gray}{\text{ (Central Angle of sector)}} \\ ratio &= \frac{60}{360} = \frac{1}{6} \color{gray}{\text{ (ratio of ca to circle angle which is 360 degrees)}} \end{align}
So now we can calculate:
\begin{align} al = \frac{1}{6} \times 24\pi &= 4\pi \color{gray}{\text{ (arc length of SECTOR = ratio X circumference of circle)}} sa &= \frac{1}{6} \times 144per = 24\pi \color{gray}{\text{ (sector area = ratio X area of circle)}} \end{align}
So my question is: What is meant by the perimeter of a Sector. Is it the arch length or the are of a Sector? And what is $24 + 4\pi$?