Grave of the fireflies

Very very very odd law, is it not? Right to exist?? What does that even mean and why would a government force you to subscribe to it?

Draw a symmetrical thingy, the calculations are then simple. I’ll let you figure out on your own what calculation is connected with what geometry:

sqrt(24²⁺⁷2) = 25 25 + 7 = 32 sqrt(32²⁺²⁴2)=40 40/2=20 x = sqrt(25^2-202)=15