Question:
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 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
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The angle between two planes can be found using the dot product of their normal vectors.
Updated On: Jan 12, 2026
- 120°
- \( \cos^{-1}\left( \frac{17}{31} \right) \)
- 30°
- 90°
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The Correct Option is B
Solution and Explanation
Step 1: Calculate the Normal Vectors.
To find the angle between the two faces, first calculate the normal vectors of the planes formed by the points. The dot product formula can be used to find the angle.
Step 2: Conclusion.
The correct answer is (B), \( \cos^{-1}\left( \frac{17}{31} \right) \).
To find the angle between the two faces, first calculate the normal vectors of the planes formed by the points. The dot product formula can be used to find the angle.
Step 2: Conclusion.
The correct answer is (B), \( \cos^{-1}\left( \frac{17}{31} \right) \).
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