Answer:
Step-by-step explanation:
Given identity is,
[tex]\text{tanA}=\pm\sqrt{\frac{1-\text{cos2A}}{1+\text{cos2A}}}[/tex]
To prove this identity, we will take left side of the identity,
[tex]\pm\sqrt{\frac{1-\text{cos2A}}{1+\text{cos2A}}}=\pm\sqrt{\frac{1-(1-2\text{sin}^2A)}{1+(2\text{cos}^2A-1)} }[/tex]
[tex]=\pm\sqrt{\frac{1-1+2\text{sin}^2A}{1+2\text{cos}^2A-1} }[/tex]
[tex]=\pm\sqrt{\frac{2\text{sin}^2A}{2\text{cos}^2A} }[/tex]
[tex]=\pm(\sqrt{\text{tan}^2A})[/tex]
[tex]=\text{tanA}[/tex] [Right side of the identity]
Hence, proved.
