What name is given to the longest side of a right angled triangle?

In a right triangle, the side that is opposite of the 90° angle is the longest side of the triangle, and is called the hypotenuse.

Explanation:

This inseparable and interpenetrating relationship is reflected in the form of the Yin-Yang symbol. The small dots within each of the two energies (represented by black and white) symbolize that there is always some Yin (black) within Yang(white) and vice versa.