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Find the angle between the plane -x + y + 2z = 9 and x + 2y + z = 5. |
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Answer» Given planes are : - x + y + 2z = 9 ...(i) and x + 2y + z = 5 ...(ii) The direction cosine of the normal to the plane (1) are (-1/√6,1/√6,2/√6) and that of plane (2) are (1/√6,1/√6,2/√6). Let be the angle between given plane, then cos = (-1/√6)(1/√6) + (1/√6)(2/√6) + (2/√6)(1/√6) = (-1/6) + (2/6) + (2/6) = 1/2 ∴ θ = 60° |
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