Hello!
Here is web address where you can found a real picture and calculated problem
http://matematika.agava.ru/S_1951.html
My problem is (only) in second formula .
VBAEC=1/3*hB*SAEC=1/3*1*(1/2*EO*sin60*AC)=1/3*1/2*R*sqrt(3)/2*2*R/sqrt(2)=R^2*sqrt(6)/12
How is in area of triangle this possible( 1/2*EO*
sin60*AC) IF YOU BE SO KIND TO LOOK AT THE PICTURE ON WEB ADDRESS I` GAVE TO YOU .
PLEASE HELP!!!