The angle between the tangents from \[(\alpha ,\beta )\]to the circle \[{{x}^{2}}+{{y}^{2}}={{a}^{2}}\], is

• A. \[{{\tan }^{-1}}\left( \frac{a}{\sqrt{{{\alpha }^{2}}+{{\beta }^{2}}-{{a}^{2}}}} \right)\]
• B. \[{{\tan }^{-1}}\left( \frac{\sqrt{{{\alpha }^{2}}+{{\beta }^{2}}-{{a}^{2}}}}{a} \right)\]
• C. \[2{{\tan }^{-1}}\left( \frac{a}{\sqrt{{{\alpha }^{2}}+{{\beta }^{2}}-{{a}^{2}}}} \right)\]
• D. None of these