Question 1158585
<br>
Let the lengths of the two parts of the bisecting diagonal be x and (8-x).<br>
Let y be the length of each half of the bisected diagonal.  Then<br>
(1) x and y are the legs of a right triangle with hypotenuse 5; and
(2) (8-x) and y are the legs of a right triangle with hypotenuse 7.<br>
{{{y^2 = 5^2-x^2}}}
{{{y^2 = 7^2-(8-x)^2}}}<br>
{{{25-x^2 = 49-(64-16x+x^2)}}}
{{{25-x^2 = -15+16x-x^2}}}
{{{25 = 16x-15}}}
{{{16x = 40}}}
{{{x = 2.5}}}<br>
The length of the bisected diagonal is 2x = 5.<br>
ANSWER: 5<br>