How do they compliment each other??

ERICA :-)

... such a broad and vague question. In what aspect of geometry?

Well... one idea I can think of are the ideas of triangles.

When a person is standing, from the front, it looks like an isosceles triangle.

The person can create an equilateral triangle from the front by spreading their legs a bit (but not too much or they'll fall) If they make a right angle between the two legs, it will be a right triangle.

Perhaps if you tell us what you're trying to do, we could offer more specific answers.