Moderate -0.8 This question requires understanding periodicity of tan (period 180°) and recognizing that 690° = 720° - 30° = 4(180°) - 30°, making tan 690° = tan(-30°) = -tan 30°. While it requires explanation rather than just calculation, the concepts are fundamental and the arithmetic is straightforward, making it easier than average for AS-level.
3 In this question you must show detailed reasoning.
You are given that $\tan 30 ^ { \circ } = \frac { 1 } { \sqrt { 3 } }$.\\
Explain why $\tan 690 ^ { \circ } = - \frac { 1 } { \sqrt { 3 } }$.
\hfill \mbox{\textit{OCR MEI AS Paper 2 2021 Q3 [3]}}