MathematicsMedium202×since 2002Q5795A tetrahedron has vertices at O(0,0,0),A(1,2,1)B(2,1,3)O(0,0,0), A(1,2,1) B(2,1,3)O(0,0,0),A(1,2,1)B(2,1,3) and C(−1,1,2).C(-1,1,2).C(−1,1,2). Then the angle between the faces OABOABOAB and ABCABCABC will be :A90∘{90^ \circ }90∘Bcos−1(1935){\cos ^{ - 1}}\left( {{{19} \over {35}}} \right)cos−1(3519)Ccos−1(1731){\cos ^{ - 1}}\left( {{{17} \over {31}}} \right)cos−1(3117)D30∘{30^ \circ }30∘Check answerSkip