[" A terrahedron has vertices "P(1,2,1),Q(2,1,3),R(-1,1,2)" and "O(0,0,0)" .The angle between the "],[" fises "OPO" and "pOR" is "]

A tetrahedron has vertices P(1,2,1),Q(2,1,3),R(-1,1,2) and O(0,0,0) . The angle beween the faces OPQ and PQR is :

A tetrahedron has vertices P(1,2,1),Q(2,1,3),R(-1,1,2) and O(0,0,0) . The angle beween the faces OPQ and PQR is :

A tetrahedron has vertices O(0,0,0), A(1,2,1), B(2,1,3) and C(-1,1,2) . Then the angle between the faces OAB and ABC is

A tetrahedron has vertices O(0,0,0), A(1,2,1), B(2,1,3) and C(-1,1,2). Then the angle between the faces OAB and ABC is

A tetrahedron has vertices at O(0,0,0), A(1,2,1), B(2,1,3) and C(-1,1,2). Then the angle between the faces OAB and ABC will be

A tetrahedron has vertices O (0,0,0), A(1,2,1,), B(2,1,3) and C(-1,1,2), the angle between faces OAB and ABC will be

A tetrahedron has vertices O(0, 0,0), A(1,2,1), C(2,1,3), D (-1, 1,2) . Show that the angle between the faces OAB and ABC is cos^(-1) ((19)/(35)) .

A tetrahedron has vertices O (0, 0, 0), A (1, 2, 1), B (2, 1, 3) and C(-1, 1, 2). The angle between the faces OAB and ABC will be:

A tetrahedron has vertices O(0,0,0),A(1,2,1),B(2,1,3),a n dC(-1,1,2), then angle between face OA B and A B C will be