我们需要测量这个三角形三条边的总长度来确定它的周长。

We need to measure the total length of all three sides to determine the ___perimeter of this triangle.

工人们在花园的四周安装了篱笆。

Workers installed fences around the ___perimeter of the garden.

士兵们日夜巡逻，确保军事基地的周边安全。

Soldiers patrol day and night to secure the ___perimeters of the military base.