令t = dy/dx,dt/dx = d²y/dx²dt/dx + √(1 - t²) = 0dt/dx = - √(1 - t²)dt/√(1 - t²) = - dxarcsin(t) = - x + C₁t = sin(C₁ - x)dy/dx = sin(C₁ - x)y = - cos(C...