Hello,Originally Posted byBlain

I've attached a diagram to show you what I've calculated.

All lines PT form a cone. C is the centre of the sphere. All triangles CTP are right triangles. So the diametre of the cone's base is 2 times the height in the right triangle. The height in aright triangle(and only there) can be calculated by:

If you know the length of the three lines you only have to plug in the values and caculate the radius of the base.

Greetings

EB