I'm trying to apply the method of ehxaustion to have an approximation of the area of the circle:
I know that the task is about decomposing the circle into a great number of triangles and then summing the area. In the first figure, there are two regular polygons, the inner one and the outer one. If I use the outer polygon, I'll have the length of $h$, if I do it with the inner polygon, I'll have only the length of $b$ - how to find the other lengths? I guess there must be a connection between the angle and length of $h$ or $b$ but until now I couldn't find it. All methods for finding the area of the isoceles triangle I've found until now need $b$ and $a$ or $b$ and $h$.