题目

求下列参数方程所确定函数的二阶导数：x=a（t-sint),y=a(1-cost)

提问时间：2021-01-03

答案

dx/dt=a(1-cost)dy/dt=asinty'=sint/(1-cost)dy'/dt=[cost(1-cost)-sint*sint]/(1-cost)^2=(cost-1)/(1-cost)^2=-1/(1-cost)y"=(dy'/dt)/(dx/dt)=-1/[a(1-cost)^2]