1.

If 7l^(2)-9m^(2) + 8l + 1 = 0and we have to find equation of circle having lx + my + 1 = 0 is a tangent and we can adjust given condition as16l^(2) + 8l + 1 = 9(l^(2) + m^(2)) or (4l + 1)^(2) = 9(l^(2) + m^(2)) rArr (|1 4l+1|)/(sqrt((l^(2) + m^(2)))) = 3 Centre of circle = (4, 0) and radius = 3 when any two non parallel lines touching a circle, then centre of circle lies on angle bisector of lines. On the basis of above information, answer the following questions : If 16l^(2) + 9m^(2) = 24lm + 6l + 8m + 1 and if S be the equation of the circle having lx + my + 1 = 0 is a tangent when the equation of director circle of S is

Answer»

`X^(2) + y^(2) + 6X + 8y = 25`
`x^(2) + y^(2) - 6x + 8y = 25`
`x^(2) + y^(2) - 6x - 8y = 25`
`x^(2) + y^(2) + 6x - 8y = 25`

ANSWER :C


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