The angle between two planes is the smallest angle $$ between the normal vectors of the planes, where the directions of the normal vectors are chosen so that $0\frac{}{2}.$ Find the angle between the planes $7x4y-3z=0$ and $-4x2y6z=0.$

The angle between the planes is $$

$($Do not round until the final answer. Then round to the nearest degree as needed.$)$