Question 580221
{{{a^2+b^2=c^2}}} Start with the Pythagorean theorem.



{{{12^2+x^2=13^2}}} Plug in {{{a=12}}}, {{{b=x}}}, {{{c=13}}} 



{{{144+x^2=13^2}}} Square {{{12}}} to get {{{144}}}.



{{{144+x^2=169}}} Square {{{13}}} to get {{{169}}}.



{{{x^2=169-144}}} Subtract {{{144}}} from both sides.



{{{x^2=25}}} Combine like terms.



{{{x=sqrt(25)}}} Take the square root of both sides. Note: only the positive square root is considered (since a negative length doesn't make sense).



{{{x=5}}} Simplify the square root.



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Answer:



So the solution is {{{x=5}}}.



This means that the length of leg B is 5 units.