... Rnϕ(x)=(x,g(x))M a R3S 2 F (x, y, z)=x 2 + y 2 + z 2 − 1=0F(x, y, z)=(2x, 2y, 2z) =(0, 0, 0) S 2 S 2 2C 1F1(x, y, z)=x 2 + y 2 + z 2 − 1=0F 2 (x, y, z)=x + y + z =0(ψ, W) ... (D1ϕ(ui,vi)∆ui,D 2 ϕ(ui,vi)∆vi)dS = (D1ϕ, D 2 ϕ)dudv =EG − F 2 dudv,E = D1ϕ 2 = xu 2 + yu 2 + zu 2 G = D 2 ϕ 2 = xv 2 + yv 2 + zv 2 F = <D1ϕ, D 2 ϕ> = xuxv+ ... =If(ϕ(t))(x1) 2 (t)+···+(xn) 2 (t)dt.ϕ : U → R3,ϕ(u, v)=(x(u, v),y(u, v),z(u, v)) SSfdS =Uf ◦ ϕEG − F 2 ,E = D1ϕ 2 = xu 2 + yu 2 + zu 2 G = D 2 ϕ 2 = xv 2 + yv 2 +...