Please find below the link of similar query as asked by you :
4 ) https://www.meritnation.com/ask-answer/question/if-the-line-y-3x-k-touches-the-circle-x2-y2-16-t/math/12099839
5 ) https://www.meritnation.com/ask-answer/question/find-the-equation-of-a-circle-with-centre-2-2-and-pa/conic-sections/6300090
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4 ) https://www.meritnation.com/ask-answer/question/if-the-line-y-3x-k-touches-the-circle-x2-y2-16-t/math/12099839
5 ) https://www.meritnation.com/ask-answer/question/find-the-equation-of-a-circle-with-centre-2-2-and-pa/conic-sections/6300090
Do let us know in case of any further concerns .