Hi Fareed134,
If you want to find the other lengths of the sides, all you have to do is take the side you know (10) and subtract it from 28. Then, divide it in half to get 2 longer sides, and divide 10 in half to get the 2 shorter sides.
28-10=18
18/2=9
10/2=5
the lengths of the other sides are 9,9,5 and 5.
Hope this helps! :)