OJ Board

If you check the length of XY,
you will find that it's a little bit larger than the answer.

It implies that there will be some unused space
and you can pack lager triangle.

So I think the offical answer is wrong.

Mahbub wrote:Well..the left top triangle shouldn't be considered

I think that triangle is very important, if you check the coordinate of the points, you will find the problem

it's wrong to assume that the top triangle and the bottom one is
on the same axis.

'You can assume that when the images look exactly symmetric along a certain axis they are actually symmetric along that certain axis.'

This does not apply to case 5 as there is no axis of symmetry.

it seems that the judge have got wrong with the case of 5 triangle

the offical answer is

0.55437056466848326729919722838716
(2 + sqrt(3)) / (5 + sqrt(3))

but I got

0.554579157314857