Mathematics

Three Dimensional Geometry Planes

198 Questions

Three dimensional geometry planes involve calculating intercepts, angles between planes, and lines of intersection. These concepts are essential for advanced mathematics assessments. The questions cover spatial relationships of planar surfaces and vector equations.

Plane interceptsLine of intersectionAngle between planesVector equations of planesPoint and plane relationships

Three Dimensional Geometry Planes Questions

Multiple choice maths the plane angle between planes angle between two planes problems involving equation of plane

The equation of the plane bisecting the angle between the planes $\displaystyle 3x +4y = 4$ and $\displaystyle 6x - 2y + 3z + 5 = 0$ that contains the origin, is

  1. $\displaystyle 9x - 38y + 15z + 43 = 0$
  2. $\displaystyle 51x + 18y + 15z = 3$
  3. $\displaystyle 9x + 2y + 3z + 1 = 0$
  4. $\displaystyle 17x + 9y + 15z = 26$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Equation of given planes can be written as
 $3x+4y=4 , 6x−2y+3z+5=0$

formula is
  $\dfrac {a _1x+b _1y+c _1z+d _1}{\sqrt {a _1^2+b _1^2+c _1^2}}$ = +  or  - $\dfrac {a _2x+b _2y+c _2z+d _2}{\sqrt {a _2^2+b _2^2+c _2^2}}$

by substituting the values in the given formula we will get 

$\dfrac {3x+4y+0z+-41}{\sqrt {3^2+4^2+0^2}}$ = + or - $\dfrac {6x+-2y+3z+5}{\sqrt {6^2+(-2)^2+3^2}}$

$\Rightarrow$ $21x+28y-28 = +\  or\  - 30x-10y+160+25$

so when adding the above equation we will get $51x + 18y + 160z - 3 = 0$

is the plane bisecting the angle containing the origin, and when subtracting we will get $9x - 38y + 160z + 53 = 0$ is the other bisecting plane.

Hence the plane $51x + 18y + 160z - 3 = 0\  or\  51x + 18y + 160z  = 3$ bisects the acute angle and therefore origin lies in the acute angle.

Multiple choice maths the plane angle between planes angle between two planes problems involving equation of plane

The equation of the plane bisecting the obtuse angle between the planes $\displaystyle x+y+z= 1$ and $\displaystyle x+2y-4z= 5$ is

  1. $\displaystyle \left ( \sqrt{7}-1 \right )x+\left ( \sqrt{7}-2 \right )y+\left ( \sqrt{7}+4 \right )z+5-\sqrt{7}= 0$
  2. $\displaystyle \left ( \sqrt{7}+1 \right )x+\left ( \sqrt{7}+2 \right )y+\left ( \sqrt{7}+4 \right )z+5-\sqrt{7}= 0$
  3. $\displaystyle \left ( \sqrt{7}+1 \right )x+\left ( \sqrt{7}+2 \right )y+\left ( \sqrt{7}-4 \right )z=\sqrt{7}$
  4. None of these

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Given planes are  $ x+y+z-1=0.....(1)$ and $x+2y-4z-5=0.........(2)$
Therefore equation of planes bisecting these planes are
$\dfrac{x+y+z-1}{\sqrt{3}}=\pm\dfrac{x+2y-4z-5}{\sqrt{21}}$

$\Rightarrow x+y+z-1=\pm\dfrac{x+2y-4z-5}{\sqrt{7}}$

$\Rightarrow (\sqrt{7}-1) x+(\sqrt{7}-2)y+(\sqrt{7}+4)z = \sqrt{7}+5 ...(3)$ and $(\sqrt{7}+1) x+(\sqrt{7}+2)y+(\sqrt{7}-4)z = \sqrt{7}-5  ....(4)$
If $\theta$ is the angle between $(1)$ and $(3)$, then

$  \cos\theta = \dfrac{(\sqrt{7}-1).1+(\sqrt{7}-2).1+(\sqrt{7}+4).1}{(\sqrt{(\sqrt{7}-1)^2+(\sqrt{7}-2)^2+(\sqrt{7}+4)^2}).(\sqrt{3})}= \dfrac{3\sqrt{7}+2}{(\sqrt{40+2\sqrt{7}}).(\sqrt{3})}> \dfrac{1}{2}$

$\Rightarrow \theta > 45^\circ$
Hence, plane $(1)$ bisects the obtuse angle between the given planes.
Therefore equation of plane bisecting acute angle  between given plane is
$(\sqrt{7}-1) x+(\sqrt{7}-2)y+(\sqrt{7}+4)z = \sqrt{7}+5 $

Hence, option 'D' is correct.

Multiple choice maths the plane angle between planes angle between two planes problems involving equation of plane

Let two planes $p _{1}:2x-y+z=2$, and $p _{2}:x+2y-z=3$ are given. The equation of the bisector of angle of the planes  $P _{1}$ and $P _{2}$ which does not contains origin, is

  1. $x-3y+2z+1=0$
  2. $x+3y=5$
  3. $x+3y+2z+2=0$
  4. $3x+y=5$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Given planes are $p _{1}:2x-y+z=2$ and $p _{2}:x+2y-z=3$

Normals to the planes
$N _1:\dfrac{1}{\sqrt{6}}(2,-1,1)$
$N _2:\dfrac{1}{\sqrt{6}}(1,2,-1)$

Let $N$ be the normal vector of angle bisector
$N=  N _1+N _2$ or $ N _1-N _2$
$N = (3,1,0)$ or $(1,-3,2)$

The equation of plane is
$P = P _1+ \lambda P _2$
$P= 2x-y+z-2 + \lambda (x+2y-z -3) $

If $N = (3,1,0)$, then $\lambda = 1$,
Equation of Plane $=  P = 3x+y- 5$
It does not pass through origin.

Hence, option D is correct.
Multiple choice

What is the relationship between a point, a line, and a plane in Euclidean geometry?

  1. A point is a zero-dimensional object, a line is one-dimensional, and a plane is two-dimensional.

  2. A point is a one-dimensional object, a line is two-dimensional, and a plane is three-dimensional.

  3. A point is a two-dimensional object, a line is three-dimensional, and a plane is four-dimensional.

  4. A point is a three-dimensional object, a line is four-dimensional, and a plane is five-dimensional.

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In Euclidean geometry, a point has no dimensions, a line has one dimension (length), and a plane has two dimensions (length and width).

Multiple choice

What is the equation of the plane that passes through the point (1, 2, 3) and has normal vector n = (2, -1, 3)?

  1. 2x - y + 3z = 8

  2. 2x + y - 3z = 8

  3. 2x - y - 3z = 8

  4. 2x + y + 3z = 8

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The equation of a plane that passes through a point (x0, y0, z0) and has normal vector n = (a, b, c) is given by the formula a(x - x0) + b(y - y0) + c(z - z0) = 0. Substituting the given values, we get 2(x - 1) - 1(y - 2) + 3(z - 3) = 0, which simplifies to 2x - y + 3z = 8.

Multiple choice

What is the Miller index for the plane that intersects the x-axis at 2a, the y-axis at 3b, and the z-axis at 4c?

  1. (234)

  2. (324)

  3. (423)

  4. (432)

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The Miller index for a plane is determined by the reciprocals of the intercepts of the plane with the crystallographic axes. In this case, the Miller index is (234).

Multiple choice

Find the equation of the plane that passes through the point ((1, 2, 3)) and has normal vector (\vec{n} = \langle 2, -1, 3 \rangle).

  1. \(2x - y + 3z = 8\)
  2. \(2x - y + 3z = 10\)
  3. \(2x - y + 3z = 12\)
  4. \(2x - y + 3z = 14\)
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

To find the equation of the plane, we can use the point-normal form: (\vec{r} \cdot \vec{n} = d), where (\vec{r}) is a vector from the origin to any point on the plane, (\vec{n}) is the normal vector, and (d) is a constant. Plugging in the given values, we get: ((x - 1) \cdot 2 + (y - 2) \cdot (-1) + (z - 3) \cdot 3 = d) which simplifies to: (2x - y + 3z = d). Since the plane passes through the point ((1, 2, 3)), we can plug in these values to find the value of (d): (2(1) - (2) + 3(3) = d) which gives (d = 10). Therefore, the equation of the plane is: (2x - y + 3z = 10).

Multiple choice

What is the equation of the plane passing through the points (1, 2, 3), (2, 3, 4), and (3, 4, 5)?

  1. x + y + z = 9

  2. x + 2y + 3z = 14

  3. 2x + 3y + 4z = 22

  4. 3x + 4y + 5z = 30

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

To find the equation of the plane, we can use the vector equation of a plane: r = r0 + s * v1 + t * v2, where r0 is a point on the plane, v1 and v2 are vectors parallel to the plane, and s and t are scalar parameters. We can choose r0 to be the point (1, 2, 3), and v1 and v2 to be the vectors (2, 3, 4) - (1, 2, 3) = (1, 1, 1) and (3, 4, 5) - (1, 2, 3) = (2, 2, 2), respectively. Substituting these values into the vector equation, we get: r = (1, 2, 3) + s * (1, 1, 1) + t * (2, 2, 2). To convert this into an equation of the plane, we can set s = x - 1 and t = y - 2, which gives: r = (1, 2, 3) + (x - 1) * (1, 1, 1) + (y - 2) * (2, 2, 2). Expanding this equation, we get: r = (1 + x - 1, 2 + y - 2, 3 + x - 1 + 2y - 4) = (x, y, x + 2y - 3). Therefore, the equation of the plane is x + 2y + 3z = 14.

Multiple choice

Find the distance from the point (2, 3, 4) to the plane 2x + 3y - z = 10.

  1. 1

  2. 2

  3. 3

  4. 4

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The distance from a point (x0, y0, z0) to a plane Ax + By + Cz + D = 0 is given by the formula: distance = |Ax0 + By0 + Cz0 + D| / √(A^2 + B^2 + C^2). Substituting the values of the point and the plane, we get: distance = |2 * 2 + 3 * 3 - 4 * 4 + 10| / √(2^2 + 3^2 + (-1)^2) = |4 + 9 - 16 + 10| / √(4 + 9 + 1) = |7| / √14 = 7 / √14 ≈ 2. Therefore, the distance from the point (2, 3, 4) to the plane 2x + 3y - z = 10 is approximately 2 units.

Multiple choice

Which of the following is the equation of the line of intersection of the planes x + y + z = 6 and 2x - y + z = 5?

  1. x = 1 + 2t, y = 3 - t, z = 2 + t

  2. x = 1 - 2t, y = 3 + t, z = 2 - t

  3. x = 1 + t, y = 3 - 2t, z = 2 + t

  4. x = 1 - t, y = 3 + 2t, z = 2 - t

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

To find the line of intersection of two planes, we can solve the system of equations formed by the two plane equations. Substituting the second equation into the first equation, we get: x + y + (2x - y + z) = 6, which simplifies to 3x + z = 4. This equation represents a plane parallel to the y-axis. To find the line of intersection, we can choose a point on this plane, such as (1, 0, 1), and find the direction vector of the line. The direction vector can be found by taking the cross product of the normal vectors of the two planes. The normal vector of the first plane is (1, 1, 1), and the normal vector of the second plane is (2, -1, 1). Taking the cross product of these vectors, we get: (1, 1, 1) x (2, -1, 1) = (-2, -3, 3). Therefore, the direction vector of the line of intersection is (-2, -3, 3). Using the point (1, 0, 1) and the direction vector (-2, -3, 3), we can write the parametric equations of the line of intersection as: x = 1 - 2t, y = 0 - 3t = -3t, z = 1 + 3t.

Multiple choice

Find the angle between the planes 2x + y - z = 3 and x - y + 2z = 5.

  1. 30°

  2. 45°

  3. 60°

  4. 75°

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The angle between two planes can be found using the formula: angle = cos^-1((n1 · n2) / (|n1| * |n2|)), where n1 and n2 are the normal vectors of the planes. The normal vector of the first plane is (2, 1, -1), and the normal vector of the second plane is (1, -1, 2). Substituting these values into the formula, we get: angle = cos^-1(((2, 1, -1) · (1, -1, 2)) / (|(2, 1, -1)| * |(1, -1, 2)|)) = cos^-1((2 - 1 + 2) / (√(2^2 + 1^2 + (-1)^2) * √(1^2 + (-1)^2 + 2^2))) = cos^-1(3 / √6 * √6) = cos^-1(3 / 6) = cos^-1(1/2) ≈ 60°. Therefore, the angle between the planes 2x + y - z = 3 and x - y + 2z = 5 is approximately 60°.

Multiple choice

Which of the following is the equation of the tangent plane to the surface (z = x^2 + y^2) at the point ((1, 2, 5))?

  1. \(z = 5 + 2x + 4y\)
  2. \(z = 5 + 2x - 4y\)
  3. \(z = 5 - 2x + 4y\)
  4. \(z = 5 - 2x - 4y\)
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

To find the equation of the tangent plane, we need to find the partial derivatives of the function (f(x, y) = x^2 + y^2) and evaluate them at the given point. The partial derivatives are (f_x(x, y) = 2x) and (f_y(x, y) = 2y). At the point ((1, 2, 5)), the partial derivatives are (f_x(1, 2) = 2) and (f_y(1, 2) = 4). Using the point-normal form, the equation of the tangent plane is (z - 5 = 2(x - 1) + 4(y - 2)), which simplifies to (z = 5 + 2x + 4y).

Multiple choice

What is the intersection of two planes called?

  1. Line

  2. Point

  3. Plane

  4. Ray

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The intersection of two planes is a line.

Multiple choice

What is the equation of a plane in three-dimensional space?

  1. $Ax + By + Cz = D$
  2. $Ax^2 + By^2 + Cz^2 = D$
  3. $Ax + By = C$
  4. $Ax + By + Cz + D = 0$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The equation of a plane in three-dimensional space is given by $Ax + By + Cz + D = 0$, where A, B, C, and D are constants.

Multiple choice

What is the equation of a line that is parallel to the plane $Ax + By + Cz + D = 0$ and passes through the point $(x_0, y_0, z_0)$?

  1. $x = x_0 + At$, $y = y_0 + Bt$
  2. $x = x_0 + At$, $y = y_0 + Bt$, $z = z_0 + Ct$
  3. $x = x_0 + At + Ct^2$, $y = y_0 + Bt + Dt^2$
  4. $x = x_0 + At$, $y = y_0 + Bt$, $z = z_0 + Ct + Dt^2$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The equation of a line that is parallel to the plane $Ax + By + Cz + D = 0$ and passes through the point $(x_0, y_0, z_0)$ is given by $x = x_0 + At$, $y = y_0 + Bt$, $z = z_0 + Ct$, where A, B, and C are the coefficients of the plane equation.