let n be Element of NAT ; for r being real number
for x being Point of (TOP-REAL n) holds Ball x,r misses Sphere x,r
let r be real number ; for x being Point of (TOP-REAL n) holds Ball x,r misses Sphere x,r
let x be Point of (TOP-REAL n); Ball x,r misses Sphere x,r
assume
not Ball x,r misses Sphere x,r
; contradiction
then consider q being set such that
A1:
q in Ball x,r
and
A2:
q in Sphere x,r
by XBOOLE_0:3;
reconsider q = q as Point of (TOP-REAL n) by A1;
|.(q - x).| = r
by A2, Th9;
hence
contradiction
by A1, Th7; verum