The angle between two planes is the smallest angle
\theta between the normal vectors of the planes, where the directions of the normal vectors are chosen so that
0<=\theta <=(\pi )/(2). Find the angle between the planes
6x+2y-3z=0and
-7x+y+6z=0. The angle between the planes is
?(Do not round until the final answer. Then round to the nearest degree as needed.)