Sides of right triangle in A.P., perimeter 36.
Let sides be (a-d,\ a,\ a+d) with hypotenuse (a+d).
[ (a-d)^2+a^2=(a+d)^2 ] As in Q22 of 6.2: (a=4d)
Sides: (3d,\ 4d,\ 5d)
[ 3d+4d+5d=36\implies 12d=36\implies d=3 ]
Sides: (9,\ 12,\ 15)
Answer: (9,\ 12,\ 15)