Solución

v(t)=2sentj+3costk,a(t)=2costj3sentk,rapidez   =4sen2t+9cos2t\bold{v}(t)=−2sent\bold{j}+3cost\bold{k}, \bold{a}(t)=−2cost\bold{j}−3sent\bold{k},\\ \text{rapidez }\; =\sqrt{4sen^2t+9cos^2t}