Question 1055099
Labeling segment AC as d,
segment AD as c,
segment DC as a,


First you can find if you like, d, as part of the upper right triangle.
{{{d^2=6^2+8^2}}}
{{{d=sqrt(36+64)}}}
{{{d=sqrt(100)}}}
{{{d=10}}}



Now deal with perimeter for the entire figure and Pythagorean relationship of the lower Triangle ACD.
{{{system(6+8+a+c=64,100+a^2=c^2)}}}
Notice that this uses two unknown variables a and c in two equations, so solvable.