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Mathematics

Choose the correct option and justify your choice :

2 tan 30°1 + tan230°=\dfrac{\text{2 tan 30°}}{\text{1 + tan}^2 30°} =

  1. sin 60°

  2. cos 60°

  3. tan 60°

  4. sin 30°

Trigonometric Identities

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Answer

Solving,

2 tan 30°1 + tan230°=2×131+(13)2=231+13=233+13=2343=2×34×3=32=sin 60°.\Rightarrow \dfrac{\text{2 tan 30°}}{\text{1 + tan}^2 30°} = \dfrac{2 \times \dfrac{1}{\sqrt{3}}}{1 + \Big(\dfrac{1}{\sqrt{3}}\Big)^2} \\[1em] = \dfrac{\dfrac{2}{\sqrt{3}}}{1 + \dfrac{1}{3}} \\[1em] = \dfrac{\dfrac{2}{\sqrt{3}}}{\dfrac{3 + 1}{3}} \\[1em] = \dfrac{\dfrac{2}{\sqrt{3}}}{\dfrac{4}{3}} \\[1em] = \dfrac{2 \times 3}{4 \times \sqrt{3}} \\[1em] = \dfrac{\sqrt{3}}{2} \\[1em] = \text{sin 60°}.

Hence, Option 1 is the correct option.

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