JEE Main 2019 Mathematics question
A tetrahedron has vertices P(1, 2, 1), Q(2, 1, 3), R(−1, 1, 2) and O(0, 0, 0). The angle between the faces OPQ and PQR is:
Answer: (C)
Solution
Normals (5, −1, −3) and (1, −5, −3): cos θ = 19/35.
A tetrahedron has vertices P(1, 2, 1), Q(2, 1, 3), R(−1, 1, 2) and O(0, 0, 0). The angle between the faces OPQ and PQR is:
Normals (5, −1, −3) and (1, −5, −3): cos θ = 19/35.