Question

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

• A. $-2$
• B. $2$
• C. $\pm 2$
• D. None of these

Answer 1

The correct option is B $2$

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