NTA Abhyas 2020 · Mathematics · Hyperbola
D. π\piπ
e2=1+cos2θ(1+sinθ)2=43⇒cos2θ(1+sinθ)2=13e^{2} = 1 + \dfrac{\cos^{2} \theta}{\left(1 + sin \theta\right)2} = \dfrac{4}{3} ⇒ \dfrac{\cos^{2} \theta}{\left(1 + sin \theta\right)2} = \dfrac{1}{3}e2=1+(1+sinθ)2cos2θ=34⇒(1+sinθ)2cos2θ=31⇒[cosθ1+sinθ]2=13⇒[sin(π2−θ)1+cos(π2−θ)]2=13⇒ \left[\dfrac{cos \theta}{1 + sin \theta}\right]2 = \dfrac{1}{3} ⇒ \left[\dfrac{\sin \left(\dfrac{\pi}{2} - \theta\right)}{1 + \cos \left(\dfrac{\pi}{2} - \theta\right)}\right]2 = \dfrac{1}{3}⇒[1+sinθcosθ]2=31⇒1+cos(2π−θ)sin(2π−θ)2=31⇒tan2(π4−θ2)=13⇒ \tan^{2} \left(\dfrac{\pi}{4} - \dfrac{\theta}{2}\right) = \dfrac{1}{3}⇒tan2(4π−2θ)=31π4−θ2=−π6,π6⇒θ2=π4−π6,π4+π6\dfrac{\pi}{4} - \dfrac{θ}{2} = \dfrac{- \pi}{6}, \dfrac{\pi}{6} ⇒ \dfrac{θ}{2} = \dfrac{\pi}{4} - \dfrac{\pi}{6}, \dfrac{\pi}{4} + \dfrac{\pi}{6}4π−2θ=6−π,6π⇒2θ=4π−6π,4π+6πθ=π2±π3=π6,5π6\theta = \dfrac{\pi}{2} \pm \dfrac{\pi}{3} = \dfrac{\pi}{6}, \dfrac{5\pi}{6}θ=2π±3π=6π,65π
Hence, the required sum =π= \pi=π