设x=lncos t ,y=sin t - t*cos t求d^2 y\(d x^2)那个d^2 y dx^2 呢

设x=lncos t ,y=sin t - t*cos t求d^2 y\(d x^2)那个d^2 y dx^2 呢
设x=lncos t ,y=sin t - t*cos t
求d^2 y\(d x^2)
那个d^2 y dx^2 呢

设x=lncos t ,y=sin t - t*cos t求d^2 y\(d x^2)那个d^2 y dx^2 呢
d^2 y\(d x^2)=(d^2y\dxdt)*(dt\dx)
dx=-tant dt
dy=tsint dt
dy\dx=-tcost (3)
dt\dx=-1\tant
对(3)式微分d^2y\dxdt=-cost+tsint
(d^2y\dxdt)*(dt\dx)=(-cost+tsint)\(-tant)