Question

If $y=\sqrt{\left(\frac{1+cos2\theta }{1-cos2\theta }\right)},\frac{dy}{dx}at\theta =\frac{3\pi }{4}$ is

• A. $-2$
• B. $2$
• C. $\pm 2$
• D. $noneofthese$

Answer 1

The correct option is B $2$

$y=\sqrt{\left(\frac{1+cos2\theta }{1-cos2\theta }\right)}=|cot\theta |=-cot\theta (\theta =\frac{3\pi }{4})\therefore \frac{dy}{d\theta }=cose{c}^2\theta {\frac{dy}{d\theta }}_{\theta =\frac{3\pi }{4}}=(\sqrt{2}{)}^2=2$