найти 2 производную
x`_(t)=a*(1-cost) y`_(t)=a(-(-sint))=asint y`_(x)=y`_(t)/x`_(t)=sint/*(1-cost) y``_(x)=(y`_(x))`_(t)/x`_(t)= =((sint)`*(1-cost)-(1-cost)`*sint)/a*(1-cost)^3= =(cost-cos^2t-sin^2t)/a(1-cost)^3=(cost-1)/(a(1-cost)^3=-1/(a*(1-cost)^2)