Introduction to Trigonometry
CH08 Question Bank
CBSE_CH08_QUESTION_BANK
Grade 10
Question:
If $A=30^\circ$, verify that $\tan 2A = \dfrac{2\tan A}{1-\tan^2A}$.
Step-by-Step Solution
Key Concept: Substitute $A=30^\circ$ on both sides and check they match.
LHS: $\tan2A=\tan60^\circ=\sqrt3$. [1.0 Mark]
RHS: $\dfrac{2\tan30^\circ}{1-\tan^230^\circ}=\dfrac{2/\sqrt3}{1-1/3}=\dfrac{2/\sqrt3}{2/3}=\sqrt3$. Since LHS $=$ RHS, verified. [1.0 Mark]
Correct Answer:
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