Q5 of 63 Page 202

If the lines 3x – 4y + 4 = 0 and 6x – 8y – 7 = 0 are tangents to a circle, then find the radius of the circle.

Since both lines are parallel & tangent to the circle. Then distance between these two lines must be the diameter of the circle.


Lines:


3x - 4y + 4 = 0


3x - 4y - 3.5 = 0 (Equating the co-efficient of the equation)


Distance (between 2 lines) = for the two given equations,


ax + by + c = 0 &ax + by + p = 0


Distance = = units


Radius =


=0.75 units.


Hence, the radius of the circle is 0.75 units.


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