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CBSE Class 12 Math 2009 Solved Paper
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Question : 27 of 29
Marks:
+1,
-0
Find the equation of the plane passing through the point (-1, 3, 2) and perpendicular to each of the planes x + 2y + 3z = 5 and 3x + 3y + z = 0.
Solution:
Let the equation of the plane be, A + B + C = 0 Plane passes through the point (-1, 3, 2) ∴ A (x + 1) + B (y - 3) + C (z - 2) = 0 ... (i) Now applying the condition of perpendicularity to the plane (i) with planes x + 2y + 3z = 5 and 3x + 3y + z = 0, we have A + 2B + 3C = 0 3A + 3B + C = 0 Solving we get A + 2B + 3C = 0 9A + 9B + 3C = 0 By cross multiplication, we have, = = ⇒ = = ⇒ = = ⇒ = = ⇒ A = 7λ ; B = - 8λ ; C = 3λ By substituting A and C in equation (i), we get, Substituting the values of A, B and C in equation (i), we have, 7λ (x + 1) - 8λ (y - 3) + 3λ (z - 2) = 0 ⇒ 7x + 7 - 8y + 24 + 3z - 6 = 0 ⇒ 7x - 8y + 3z + 25 = 0
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