The one on the right in the cross section is right, and the one on the left should be the same as the one on the right.

Obviously P3C= 1, P3C/P3D=P4C/D 1D, so P4C=2/3. So C 1P4=4/3.

In the P4FC of RT triangle, P4C=2/3 and CF= 1, so P4F= root13/3; In the RT triangle D 1C 1P4, C 1P4=4/3 and D 1C65438.

So D 1P4+FP4= root number 13. Because EF= root number 2, the section perimeter is (root number 2+2 times root number 13).