Q9 of 63 Page 202

If the line touches the circle x2 + y2 = 16, then find the value of k.

Since, the equation of a circle having centre (h,k), having radius as "r" units, is


(x – h)2 + (y – k)2 = r2


(x – 0)2 + (y – 0)2 = 42


Perpendicular Distance between a point (0, 0) & the line or


Perpendicular Distance (Between a point and line) = , whereas the point is and the line is expressed as ax + by + c = 0



(Radius = 4, Given)



Hence, the required value of k is 8.


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