Since furface Area by the revolution obout x axiy is given by{:[A=int_(a)^(b)2pi ysqrt(1+((dy)/(dx))^(2))dx],[:.y=sin x quad x in10","3pi7],[=>A=int_(0)^(3pi)2pi sin xsqrt(1+((d^(2)sin x)/(dx))^(2))dx],[=int_(0)^(3pi)2pi sin xsqrt(1+cos^(2)x)dx],[" let "cos x=t=>-sin xdx=d*t],[" At "x=0","t=cos 0=1],[" At "x=3pi","t=cos 3pi=-1],[=>quad A=int_(1)^(-1)2pi sin xsqrt(1+t^(2))(dt)/((-sin x))],[=-int_(1)^(-1)2pisqrt(1+t^(2))d ... See the full answer