var('a,t')
x=a*cos(t)
y=a*sin(t)
y=(a*a-x^2)^0.5
z=diff(y,t)/diff(x,t)
show(integrate(2*pi*y*(1+z*z)^0.5,x,0,pi))

Hirst-11.4 (last edited 2010-12-18 10:16:10 by chandrahas.kolla)