Trigonometric Ratios and Identities
Tangent Subtraction
JEE Main 2023
Grade 11
Question:
Find the value of $\tan 9^\circ - \tan 27^\circ - \tan 63^\circ + \tan 81^\circ$.
Step-by-Step Solution
Key Concept: Rewrite as $(\tan 9^\circ + \cot 9^\circ) - (\tan 27^\circ + \cot 27^\circ)$. Use $\tan \theta + \cot \theta = 2/ \sin 2\theta$ and values of $\sin 18^\circ$, $\sin 54^\circ$.
The detailed step-by-step mathematical proof is available inside the Mathbee app workspace.
Correct Answer: 4