Question 1203786
Because you want x=y or y=x


{{{sqrt((x-10)^2+(y-(-10))^2)=sqrt((x-(-4))^2+(y-6)^2)}}}

{{{sqrt((x-10)^2+(y+10)^2)=sqrt((x+4)^2+(y-6)^2)}}}

sq. both sides, and making substitution

{{{(x-10)^2+(x+10)^2=(x+4)^2+(x-6)^2}}}

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The point, (-37,-37)