Distance between two points $$(x_1 , y_1)$$ and $$(x_2 , y_2)$$ = $$\sqrt{(y_2 - y_1)^2 + (x_2 - x_1)^2}$$
Now, distance between points (7,7) and (k,-5) = 13
=> $$\sqrt{(-5-7)^2 + (k - 7)^2} = 13$$
=> $$144 + (k^2 - 14k + 49) = (13)^2 = 169$$
=> $$k^2 - 14k = 169 - 49 - 144$$
=> $$k^2 - 14k + 24 = 0$$
=> $$k^2 - 12k - 2k + 24 = 0$$
=> $$k(k - 12) - 2(k - 12) = 0$$
=> $$(k - 12) (k - 2) = 0$$
=> $$k = 12 , 2$$
=> Ans - (D)
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