Practicing Success
If (cosec 2x + cot 2x) (5-2\(\sqrt {6}\))=1, find the value of cosx |
\(\sqrt { \frac{5-2 \sqrt {6}}{10} }\) \(\sqrt {\frac{\sqrt {6}}{5} + \frac{1}{2}}\) 0 \(\sqrt { \frac{5+2 \sqrt {6}}{40} }\) |
\(\sqrt {\frac{\sqrt {6}}{5} + \frac{1}{2}}\) |
We know cosec2θ - cot2θ = 1 (cosecθ + cotθ)(cosec θ - cotθ) = 1 ⇒ cosec 2x + cot 2x = \(\frac{1}{5-2 \sqrt {6}}\) ⇒ cosec 2x - cot 2x = 5-2\(\sqrt {6}\) 2 cosec 2x = 10 cosec 2x = \(\frac {5}{1}\) we know ⇒ cos 2x = \(\frac{2\sqrt {6}}{5}\) 1 - 2sin2x = 2cos2x - 1 = \(\frac{2\sqrt {6}}{5}\) 2cos2x - 1 = \(\frac{2\sqrt {6}}{5}\) 2cos2x - 1 = \(\frac{2\sqrt {6}+5}{5}\) cosx = \(\sqrt {\frac{2\sqrt {6}+5}{5}}\) = \(\sqrt {\frac{\sqrt {6}}{5} + \frac{1}{2}}\) = \(\sqrt {\frac{\sqrt {6}}{5} + \frac{1}{2}}\) |