The conservation of energy is a because it is has been demonstrated without exception under certain stated conditions.

More details, but if Formula is a choice then that is your answer.

1) The square section

The side length of the square is 15m.

You can use Pythagora's theorem to find the length of the diagonal:

Diagonal ^2 = (15m)^2 + (15m^2) = 450 m^2

=> Diagonal = √(450m^2) = 21.21m

2)  The small rectangle section

The sides of this rectangle are 23 - 15 = 8 m and 15 m

Now use the Pythagora's theorem:

diagonal^2 = (8m)^2 + (15m)^2 = 289 m^2 =>

diagonal = √(289m^2) = 17 m

3) Then the sum of the lengths of the diagonals of the two sections  is 17m + 21.21 m = 38.21

38.21 m