3.
\begin{figure}[h]
\includegraphics[alt={},max width=\textwidth]{fa4afaf4-fe5d-4f3a-b3de-9600d5502a49-06_490_458_248_806}
\captionsetup{labelformat=empty}
\caption{Figure 1}
\end{figure}
Figure 1 shows a sector \(A O B\) of a circle with centre \(O\), radius 5 cm and angle \(A O B = 40 ^ { \circ }\) The attempt of a student to find the area of the sector is shown below.
$$\begin{aligned}
\text { Area of sector } & = \frac { 1 } { 2 } r ^ { 2 } \theta
& = \frac { 1 } { 2 } \times 5 ^ { 2 } \times 40
& = 500 \mathrm {~cm} ^ { 2 }
\end{aligned}$$
- Explain the error made by this student.
- Write out a correct solution.