Find the acceleration of a particle with the given position function. r(t)=9 sinti + 10 tj - 6 costk O a(t)=-9 sinri - 9 costj Oa(t)= -9 sinri + 6 costk O a(t)=9 sinfi - 10 rj O a(t) = -9 sinti +9 costj O a(t)= -9 sinti + 10 costk