Here, {TAIL ~ equation} denotes {HEAD ~ the spherical surface} when K=A=B=C=0 
Here , { TAIL ~ equation } denotes { HEAD ~ the spherical surface } when K = A = B = C=0
OTH OTH TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH