Skip to content
Exercise 7.2 · Q32

Q.Find the

(i) lengths of the principal axes
(ii) co-ordinates of the foci
(iii) equations of directrics
(iv) length of the latus rectum
(v) distance between foci
(vi) distance between directrices of the ellipse: 3x2+4y2=13x^2 + 4y^2 = 1.
Maharashtra MsbshseTextbookSubjectiveImportance★★★★★est
21% · 32/151 Questions
🔒 Locked · start free trial →

You're viewing a preview — the full solution, concept, methods & PYQ mapping are locked.

Start your 14-day free trial to unlock the full solution →

3x2+4y2=1⇒x21/3+y21/4=13x^2+4y^2=1 \Rightarrow \dfrac{x^2}{1/3}+\dfrac{y^2}{1/4}=1. So a2=13, b2=14⇒a=33, b=12a^2=\dfrac13,\,b^2=\dfrac14 \Rightarrow a=\dfrac{\sqrt3}{3},\,b=\dfrac12.

  1. Major axis =2a=233=2a=\dfrac{2\sqrt3}{3}; minor axis =2b=1=2b=1.
  2. e2=1−b2a2=1−1/41/3=1−34=14⇒e=12e^2=1-\dfrac{b^2}{a^2}=1-\dfrac{1/4}{1/3}=1-\dfrac34=\dfrac14 \Rightarrow e=\dfrac12. Foci (±ae,0)=(±36,0)(\pm ae,0)=\left(\pm\dfrac{\sqrt3}{6},0\right).
  3. Directrices: x=±ae=±233x=\pm\dfrac{a}{e}=\pm\dfrac{2\sqrt3}{3}.
  4. Latus rectum =2b2a=2(1/4)3/3=1/23/3=32=\dfrac{2b^2}{a}=\dfrac{2(1/4)}{\sqrt3/3}=\dfrac{1/2}{\sqrt3/3}=\dfrac{\sqrt3}{2}.
  5. Distance between foci =2ae=33=2ae=\dfrac{\sqrt3}{3}. …

Unlock everything free for 14 days

  • Full step-by-step solutions
  • Concept-first explanations
  • Methods, shortcuts & mistakes
  • PYQ mapping + timed mock tests

Full access for 14 days. No credit card required.