Ex 10.2, 8 Find the equation of the parabola that satisfies the following conditions: Focus (0, –3); directrix y = 3 Since focus lies on y-axis Hence equation is either x2 = 4ay & x2 = −4ay Now focus has a negative y co-ordinate So, we have to use equation x2 = −4ay Coordinate of focus = (0, −a) (0, −a) = (0, −3) −a = −3 a = 3 Equation of parabola is x2 = −4ay x2 = −4(3)y x2 = −12y

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Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.