The curves: r1(t)= and r2(t)= intersect at the origin. Find the acute angle of intersection (in radians)

The curves: r1(t)=<-t,t^6,4t^4> and r2(t)=<sin(3t),sin(-2t),t-pi> intersect at the origin. 

Find the acute angle of intersection (in radians) on the domain 0<theta< pi/2, to at least two decimal places.