Q29 of 45 Page 1

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.

We know, the plane passing through (x1, y1, z1) and having direction ratios of normal as A, B and C have equation


A(x – x1) + B(y – y1) + C(z – z1) = 0


Now, required plane passes through (-1, 3, 2) and let A, B and C be the direction ratios of normal of given plane


Then, equation of the line is


A(x + 1) + B(y – 3) + C(z – 2) = 0


Since the line is perpendicular to the planes x + 2y + 3z = 5 and 3x + 3y + z = 0,normal to plane would be perpendicular to normal of these two planes


Also, we know that


is perpendicular to both and


Therefore, we have to find the cross product of normal of plane


x + 2y + 3z = 5 [Normal ]


3x + 3y + z = 0 [Normal ]


Hence, required normal





Hence, direction ratios are -7, 8, -3


And equation of plane:


-7(x + 1) + 8(y – 3) – 3(z – 2) = 0


-7x – 7 + 8y – 24 – 3z + 6 = 0


7x – 8y + 3z + 25 = 0


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