1. The problem statement, all variables and given/known data A particle travels along a path C in R^3 which velocity v(t) =<t^2, cos(pi*t), t> at time t. Assume that the particle's initial position is at the point p=(1, 0, -1). Find all times t at which the particle is accelerating in a direction that is perpendicular to the plane 4x+2z= squareroot(squareroot(squareroot(2))). 2. Relevant equations 3. The attempt at a solution I have calculated that the point f(t) = (1/3*t^3, sin(pi*t)/pi +1, .5t^2 -1) at time t, that the acceleration a(t) = <2t,-pi*sin(pi*t), 1> for time t, and that the normal of the plane is n=<4,0,2> and so the direction vector of the particle should be equal to <4,0,2> but i don't know what to do after that? thanks!