side one is 5 side two is 10 and the third side is 13. 28 is not divisible by three so if one side i 5 ft longer and another side is 8 ft longer then you add them 5+8=13 then subtract 13 from the perimeter 28-13=15 then divide 15 by 3 and get 5 5 5. add 5 (5+5) (5+8).
11. Similar 1/2
12. Similar 2
13. no
14. no
15. No, they are not congruent because rectangles do not have equal sides, so the length of one triangle could be longer than the other and the width ozone can be shorter than the other.
16. Yes