The length of the plank is 3m> The height of the door is 2m. Obviously, the plank should be sent through the door from beginning to end.

But the width of the board is 2.2m >: the height of the door is 2m, so it must pass obliquely.

In this way, it is necessary to calculate the diagonal length of the door frame, and the height and width of the door frame are needed.

Diagonal length = root number (door frame height 2+ door frame width 2) = root number 5 ≈ 2.236 > Plate width 2.2

So that the board can pass.