Radius of the Common Circle of Two Spheres

Radius of the Common Circle of Two Spheres

If the spheres have radii $$R_1,R_2$$ and centre distance $$d$$, and the common circle has radius $$\rho$$, then:

$$\rho^2=R_1^2-x^2$$

where $$x$$ is the distance from the first centre to the common-circle plane.

Usage

- Used when determining the radius of the circle of intersection.