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Statement 1: Distance of point D( 1,0,-1...

Statement 1: Distance of point D( 1,0,-1) from the plane of points A( 1,-2,0) , B ( 3, 1,2) and C( -1,1,-1) is `8/sqrt229`
Statement 2: volume of tetrahedron formed by the points A,B, C and D is `sqrt229/ 2`

A

(a) Both the statements are true and statement 2 is the correct explanation for statement 1.

B

(b) Both statements are true but statement 2 is not the correct explanation for statement 1.

C

(c) Statement 1 is true and Statement 2 is false

D

(d) Statement 1 is false and Statement 2 is true.

Text Solution

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The correct Answer is:
To solve the problem, we need to verify both statements regarding the distance of point D from the plane formed by points A, B, and C, and the volume of the tetrahedron formed by points A, B, C, and D. ### Step 1: Find the vectors AB, AC, and AD 1. **Calculate vector AB:** \[ \text{A} = (1, -2, 0), \quad \text{B} = (3, 1, 2) \] \[ \text{AB} = \text{B} - \text{A} = (3 - 1, 1 - (-2), 2 - 0) = (2, 3, 2) \] 2. **Calculate vector AC:** \[ \text{C} = (-1, 1, -1) \] \[ \text{AC} = \text{C} - \text{A} = (-1 - 1, 1 - (-2), -1 - 0) = (-2, 3, -1) \] 3. **Calculate vector AD:** \[ \text{D} = (1, 0, -1) \] \[ \text{AD} = \text{D} - \text{A} = (1 - 1, 0 - (-2), -1 - 0) = (0, 2, -1) \] ### Step 2: Find the normal vector to the plane formed by points A, B, and C To find the normal vector \( \mathbf{n} \) to the plane formed by points A, B, and C, we can use the cross product of vectors AB and AC. 1. **Calculate the cross product \( \mathbf{n} = \mathbf{AB} \times \mathbf{AC} \):** \[ \mathbf{AB} = (2, 3, 2), \quad \mathbf{AC} = (-2, 3, -1) \] \[ \mathbf{n} = \begin{vmatrix} \mathbf{i} & \mathbf{j} & \mathbf{k} \\ 2 & 3 & 2 \\ -2 & 3 & -1 \end{vmatrix} \] \[ = \mathbf{i}(3 \cdot -1 - 2 \cdot 3) - \mathbf{j}(2 \cdot -1 - 2 \cdot -2) + \mathbf{k}(2 \cdot 3 - 3 \cdot -2) \] \[ = \mathbf{i}(-3 - 6) - \mathbf{j}(-2 + 4) + \mathbf{k}(6 + 6) \] \[ = \mathbf{i}(-9) - \mathbf{j}(2) + \mathbf{k}(12) \] \[ = (-9, -2, 12) \] ### Step 3: Find the equation of the plane The equation of the plane can be expressed as: \[ -9(x - 1) - 2(y + 2) + 12(z - 0) = 0 \] Expanding this gives: \[ -9x + 9 - 2y - 4 + 12z = 0 \implies -9x - 2y + 12z + 5 = 0 \] ### Step 4: Calculate the distance from point D to the plane The distance \( d \) from point \( D(1, 0, -1) \) to the plane \( Ax + By + Cz + D = 0 \) is given by: \[ d = \frac{|Ax_0 + By_0 + Cz_0 + D|}{\sqrt{A^2 + B^2 + C^2}} \] Substituting \( A = -9, B = -2, C = 12, D = 5 \) and \( (x_0, y_0, z_0) = (1, 0, -1) \): \[ d = \frac{|-9(1) - 2(0) + 12(-1) + 5|}{\sqrt{(-9)^2 + (-2)^2 + (12)^2}} \] \[ = \frac{|-9 + 0 - 12 + 5|}{\sqrt{81 + 4 + 144}} = \frac{|-16|}{\sqrt{229}} = \frac{16}{\sqrt{229}} \] ### Step 5: Verify Statement 1 The distance calculated is \( \frac{16}{\sqrt{229}} \), which does not match the given statement \( \frac{8}{\sqrt{229}} \). Therefore, **Statement 1 is false**. ### Step 6: Calculate the volume of the tetrahedron The volume \( V \) of tetrahedron formed by points A, B, C, and D is given by: \[ V = \frac{1}{6} | \mathbf{AD} \cdot (\mathbf{AB} \times \mathbf{AC}) | \] We already have \( \mathbf{AD} = (0, 2, -1) \) and \( \mathbf{AB} \times \mathbf{AC} = (-9, -2, 12) \). 1. **Calculate the dot product:** \[ \mathbf{AD} \cdot (\mathbf{AB} \times \mathbf{AC}) = (0, 2, -1) \cdot (-9, -2, 12) = 0 \cdot -9 + 2 \cdot -2 + -1 \cdot 12 = 0 - 4 - 12 = -16 \] 2. **Calculate the volume:** \[ V = \frac{1}{6} | -16 | = \frac{16}{6} = \frac{8}{3} \] ### Step 7: Verify Statement 2 The volume calculated is \( \frac{8}{3} \), which does not match the given statement \( \frac{\sqrt{229}}{2} \). Therefore, **Statement 2 is also false**. ### Conclusion Both statements are incorrect.

To solve the problem, we need to verify both statements regarding the distance of point D from the plane formed by points A, B, and C, and the volume of the tetrahedron formed by points A, B, C, and D. ### Step 1: Find the vectors AB, AC, and AD 1. **Calculate vector AB:** \[ \text{A} = (1, -2, 0), \quad \text{B} = (3, 1, 2) \] ...
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