Question

Consider a family of circles which are passing through the point (-1, 1) and are tangent to xaxis. If (h, k) are the co-ordinates of the centre of the circles, then the set of values of k is given by the interval

• A. $0\le k\le\frac{1}{2}$
• B. $k \ge ?$
• C. $- ? \le k \le ?$
• D. $k \le ?$

Answer 1

Answer: (B)

$k \ge ?$

Answer 2

$D \ge 0$ $2k-1 \ge 0 \Rightarrow k \ge 1/2.$