If you were to slice a real igloo in half, you'd see a shape called a catenary.

如果把真正的冰屋分分，你可以看见线的形状。

This gradually sloping shape is the same one that would form if you held a chain from both ends and let it droop.

如果你拿着一根条的端，让它自由地下落，到的形状就是线。

All cables sag under their own weight, following a curve called a catenary.

所有电缆在其自身重量作用下会下垂，形一种称线的曲线。

If you watched my video about the science of igloos, you remember that this shape, called a catenary arch, distributes tension and compression more evenly than a half circle shape.

如果你看我关于冰屋原理的视频，那么你会记这种称线拱的形状比半圆形更均匀地分布张力和压力。

If you know the weight of the cable, you can use the catenary equation with the measured sag distance to estimate cable force fairly accurately.

如果你知道电缆的重量，可以使用线方程结合测量的下垂距离来相当准确地估算电缆的力。