{x = a(t - sin t)
{y = a(1 - cos t)
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)