答案是d^2y/dt^2+y=0，我做出来错的，想看看解法
答案对吗
d^2y/dx^2=d(dy/dx)/dx=d(-dy/(sintdt))/郑仿(-sintdt)=(-(d^2y/dt*sint-dy/dt*cost)/(sint)^2)dt/(-sintdt)=d^2y/dt^2/(sint)^2-dy/dt*cost/(sint)^3
原喊山纤方程可化为1/(sint)^2*d^2y/dt^2-cost/(sint^3)*dy/dt+cost/(sint)^2*dy/(sintdt)+y/(sint)^2=0
z/(sint)^2*d^y/dt^2+y/唯游(sint)^2=0，即d^2y/dt^2+y=0