First of all, it's clear from the Pythagoras' theorem that a is the square root of ^2 + ^2.

首先,根据毕达哥拉斯定理,勾股定理在西方被称为"毕达哥拉斯定理"

耶鲁公开课 - 基础物理课程节选

I take the difference in the x-values, squared, the difference in the y-values, squared, add them up, take the square root of that.

好，是毕达哥拉斯定力对不对？,求x坐标的差，然后平方，求y坐标的差，然后平方，把它们加起来，开平方。

麻省理工公开课 - 计算机科学及编程导论课程节选

If you give me a pair of numbers, Ax and Ay, that's as good as giving me this arrow, because I can find the length of the arrow by Pythagoras' theorem.

如果给我一组数字,Ax 和 Ay,就相当于给了我这个箭头示意图,因为我可以利用毕达哥拉斯定理定理求出模长

耶鲁公开课 - 基础物理课程节选