3-4-5 Triangle (1)

M1

This a 3-4-5 triangle, a special case and the most simple example of Pythagorean theorem (勾股定理 in Chinese）

You can’t see any magic in the picture above until you see the picture below. When two big circles of equal radius, a small circle and a line are tangent to each other, you’ll find a 3-4-5 triangle, easy to approve it yourself.