# Ex 11.1, 5 - Chapter 11 Class 11 Conic Sections

Last updated at May 29, 2018 by Teachoo

Last updated at May 29, 2018 by Teachoo

Transcript

Ex 11.1, 5 Find the equation of the circle with centre (–a, –b) and radius a2 −b2 We know that equation of a circle is (x – h)2 + (y – k)2 = r2 Where (h, k) is the centre & r is the radius Here Centre (h, k) = (−a, −b) So h = −a & k = −b & radius r = a2 −b2 . Putting values in (1) (x − (−a))2 + (y − (−b))2 = (a2 −b2)2 (x + a)2 + (y + b)2 = a2 − b2 x2 + a2 + 2(a)(x) + y2 + + b2 2(b)(y) = a2 – b2 x2 + a2 + 2ax + y2 + b2 + 2by = a2 – b2 x2 + y2 + 2ax + 2by + a2 + b2 = a2 – b2 x2 + y2 + 2ax + 2by + a2 + b2 − a2 + b2 = 0 x2 + y2 + 2ax + 2by + 2b2 = 0 Hence, the required equation is x2 + y2 + 2ax + 2by + 2b2 = 0

Chapter 11 Class 11 Conic Sections

Serial order wise

About the Author

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.