From point A, draw a line making $30^\circ$ anticlockwise from AB. Make it longer than $10\,\text{cm}$. Put the label C at the outer end.
Place point D on AB, $4.0\,\text{cm}$ from A. Construct a perpendicular to AB through D, and ensure it also crosses the line AC drawn in part (a)(i). Mark the point where the line through D cuts AC as E.
Construct a normal to line AC at point E.
Mark the angle between DE and the normal you have drawn as $\theta$. Measure and write down angle $\theta$.
Explain how points $P_1$ and $P_2$ are selected so that the reflected line is as accurate as possible.
In Fig. 2.2, draw a line from point A’ at $60^\circ$ anticlockwise to line A’B’. The line must be longer than $10\,\text{cm}$. Put the label C’ on the end of the line.
Mark point D’ on A’B’, $4.0\,\text{cm}$ from A’. Draw a line perpendicular to A’B’ through D’. This line must also cross A’C’. Label the point where the line through D’ cuts A’C’ as E’. Draw a normal to line A’C’ at point E’.
Write $\alpha$ on the angle between D’E’ and the normal you have drawn. Describe one practical precaution you use to make sure the normal is drawn accurately.
Measure and note angle $\alpha$.
Theory predicts that $\alpha = 2\theta$. State whether your results back up this theory. Give a reason for your answer.