The rule is that the hypotenuse of each triangle is the right-angled side of the triangle on its left. Because all triangles are similar, the proportions of the three sides of the triangle are the same. A2O is better than A 1O=2 than root number 3, so A3O must be equal to 2 than root number 3. As we all know, A2O=2, and then you can forget it yourself.