AP EAMCET Engineering 2011 Solved Paper

Given, lines
3x+4y−14=0 .......(i)
and 6x+8y+7=0 ........(ii)
are both tangents to a circle
we observe that, both lines are parallel
i.e., 3x+4y−14=0
and 3x+4y+

7

2

=0
So, radius of circle =

1

2

(distance between two parallel lines)
=

1

2

{

|7∕2+14|

√9+16

}
=

1

2

{

35∕2

5

}=

1

2

×

7

2

=

7

4