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 16m^(2) – 8l– 1 = 0, then equation of the circle having lx + my + 1 = 0 is a tangent is

Answer»

`X^(2) + y^(2) + 8x = 0`
`x^(2) + y^(2) - 8x = 0`
`x^(2) + y^(2) + 8y = 0`
`x^(2) + y^(2) - 8y = 0`

ANSWER :B


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