I'm trying to calculate the radius of the circle [tex]x^2 - 2ax + y^2 - 2ay = 0[/tex](adsbygoogle = window.adsbygoogle || []).push({});

I completed the square and got to [tex](x-a)^2 + (y-a)^2 = 2{a}^2[/tex]

That would mean the radius is [tex]\sqrt{2{a}^2}[/tex] right? Which would be [tex]\sqrt{2}\sqrt{a^2} \Rightarrow a\sqrt{2}[/tex]... but my textbook quotes the answer as [tex]\sqrt{2a}[/tex] Did I do something wrong or is my textbook incorrect?

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# Homework Help: Radius of a circle

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