# Example 12 - Chapter 11 Class 11 Conic Sections

Last updated at May 29, 2018 by Teachoo

Last updated at May 29, 2018 by Teachoo

Transcript

Example 12 Find the equation of the ellipse, whose length of the major axis is 20 and foci are (0, 5). We need to find equation of ellipse Whose length of major axis = 20 & foci are (0, 5) Since the foci are of the type (0, c) So the major axis is along the y-axis & required equation of ellipse is + = 1 From (1) & (2) c = 5 Given length of major axis = 20 & we know that Length of major axis = 2a 20 = 2a 2a = 20 a = 20 2 a = 10 Also We know that c2 = a2 b2 (5) 2 = (10) 2 b2 b2 = (10) 2 (5) 2 b2 = 100 25 b2 = 75 Equation of ellipse is 2 2 + 2 2 = 1 Putting value 2 75 + 2 (10) 2 = 1 + = 1

Chapter 11 Class 11 Conic Sections

Serial order wise

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Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.