Question 868333
I'm assuming you want to find the missing leg of the right triangle (which is x). If so, then {{{x>0}}} and solving for x gives you



{{{(sqrt(5))^2 + x^2 = 7^2}}}



{{{5 + x^2 = 49}}}



{{{x^2 = 49-5}}}



{{{x^2 = 44}}}



{{{x = sqrt(44)}}} Ignore the negative square root since {{{x>0}}}



{{{x = sqrt(4*11)}}}



{{{x = sqrt(4)*sqrt(11)}}}



{{{x = 2*sqrt(11)}}} Exact length



{{{x = 6.6332495807108}}} Approximate length (using a calculator to compute)