If \(\sec (x)=\cosh (\theta)\), then find \(\tanh ^2\left(\frac{\theta}{2}\right)\)
If \(\sec (x)=\cosh (\theta)\), then find \(\tanh ^2\left(\frac{\theta}{2}\right)\)
- \(\sec ^2\left(\frac{x}{2}\right)\)
- \(\tan ^2\left(\frac{x}{2}\right)\)
- \(\tanh ^2\left(\frac{x}{2}\right)\)
- \(\operatorname{sech}^2\left(\frac{x}{2}\right)\)
Solution
Since, \(\tan h^2\left(\frac{\theta}{2}\right)=\frac{\cosh (\theta)-1}{\cos h(\theta)+1}\)
\(\begin{aligned}
& =\frac{\sec x-1}{\sec x+1} \quad(\because \cosh \theta=\sec x \text { given }) \\
& =\frac{1-\cos x}{1+\cos x}=\frac{2 \sin ^2 \frac{x}{2}}{2 \cos ^2 \frac{x}{2}}=\tan ^2 \frac{x}{2}
\end{aligned}\)
Asked in: AP EAMCET 2020 (18 Sep Shift 1)
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