(1 point) A parametric curve r(t) crosses itself if there exist t + 8 such that r(t) = r(s). The angle of intersection is the (acute) angle between the tangent vectors r'(t) and r'(s). The parametric curver = (-2t2 - 8t - 3,-2 cos(t), t3. 37t) crosses itself at one and only one point. The point is (x, y, z) = ( Let be the acute angle between the two tangent lines to the curve at the crossing point. Then cos(0) = ).