<PRE><B>Question 1059687</B>
{{{x^2+(x-7)^2=(x+1)^2}}}


That is the equation for the description.  That is according to Pythagorean Theorem formula for right triangle.  Your already-learned algebra skills allow you to solve for x.


Simplify, collect like terms, use either factoring or general solution for quadratic formula.


{{{x^2+x^2-14x+49-x^2-2x-1=0}}}

Do the rest!</PRE>