Black Hole/ Schwarzschild

[carcosachild]

Hello :)
I had a question , i recently red a lot about black holes and i had a question about the Schwarzschild
Radius . How does that come that π is not in the equation ? The black hole is a sphere so instinctly one could think that Pi should be in the equations.. ?
P.S: I'm french and 16 so sorry for the eventuals faults :)

 

[mathman]

In geometry, you start with radius r. π comes in to get circumference, area, volume, etc.