half-circle protractor

• 半圆分度器

half-circle protractor的用法和样例：

例句

1. The actual displacement between any two points may be determined by drawing a scale diagram with a ruler and a protractor, or by using simple trigonometry.
   任何两点之间实际的位移可用比例尺和分度器画简图予以判断，或者使用简单的三角学计算之。