Hyperbola

Find the equation and length of common tangents to x^2/a^2 - y^2/b^2=1 and y^2/a^2 -x^2/b^2=1 .

Please explain how you have solved it

Answers: xÂ±y=Â±âˆš(a^2-b^2)
And
âˆš2(a^2+b^2)/âˆš(a^2-b^2)

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