Ответ:

S = π*r*l,

h = 6 см,

cos(30°) = h/l,

l = h/cos(30°) = 6/((√3)/2) = 12/√3,

tg(30°) = r/h,

r = h*tg(30°) = 6*(1/√3) = 6/√3,

S=π*(6/√3)*(12/√3) = π*6*12/3 = π*2*12 = 24π