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Question Number 51269 by peter frank last updated on 25/Dec/18

Find the ecentricity If  (1)lactus rectum is half  major axis  (2)lactus rectum is half  minor axis

FindtheecentricityIf(1)lactusrectumishalfmajoraxis(2)lactusrectumishalfminoraxis

Answered by tanmay.chaudhury50@gmail.com last updated on 25/Dec/18

1)e=(c/a)  LT   ((2b^2 )/a)=a    2b^2 =a^2     c^2 =a^2 −b^2   →for elipse     =a^2 −(a^2 /2)  =(a^2 /2)    c=±(a/(√2))     so e=(c/a)=±(a/((√2) ×a))=±(1/(√2))  for hyperbola  c^2 =a^2 +b^2   c^2 =a^2 +(a^2 /2)=((3a^2 )/2)  c=±(√(3/2))  a  e=(c/a)=±(√(3/2))   2)((2b^2 )/a)=b  a=2b  c^2 =a^2 −b^2  for ellipse  c^2 =a^2 −(a^2 /4)=((3a^2 )/4)  e=(c/a)=±((√3)/2)  for hyperbola  c^2 =a^2 +b^2   c^2 =a^2 +(a^2 /4)  c^2 =((5a^2 )/4)  e=(c/a)=±(((√5) )/2)

1)e=caLT2b2a=a2b2=a2c2=a2b2forelipse=a2a22=a22c=±a2soe=ca=±a2×a=±12forhyperbolac2=a2+b2c2=a2+a22=3a22c=±32ae=ca=±322)2b2a=ba=2bc2=a2b2forellipsec2=a2a24=3a24e=ca=±32forhyperbolac2=a2+b2c2=a2+a24c2=5a24e=ca=±52

Commented by peter frank last updated on 25/Dec/18

sir the ans given are  (1)e=±((√2)/2)  (2) e=±((√3)/2)

sirtheansgivenare(1)e=±22(2)e=±32

Commented by tanmay.chaudhury50@gmail.com last updated on 25/Dec/18

ok i have igonred ± sign...let me add ± sign

okihaveigonred±sign...letmeadd±sign

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