Math Problem Statement

Find the minimum distance between the two planes, a. P1: 2π‘₯ + 3𝑦 βˆ’ 6𝑧 = βˆ’10 and P2: 2π‘₯ + 3𝑦 βˆ’ 6𝑧 = 88. b. The point (-2, 0, 1) resides on P1. What is the nearest point on P2?

Solution

Let's solve the two parts of the problem step by step:

Part (a): Minimum Distance Between Two Planes

Given planes:

  • P1:2x+3yβˆ’6z=βˆ’10P_1: 2x + 3y - 6z = -10
  • P2:2x+3yβˆ’6z=88P_2: 2x + 3y - 6z = 88

Both planes have the same normal vector n=⟨2,3,βˆ’6⟩\mathbf{n} = \langle 2, 3, -6 \rangle. Since the planes are parallel (same normal vector), the minimum distance between them can be calculated using the formula:

Distance=∣d2βˆ’d1∣βˆ₯nβˆ₯\text{Distance} = \frac{|d_2 - d_1|}{\|\mathbf{n}\|}

where:

  • d1=βˆ’10d_1 = -10 (from the equation of P1P_1)
  • d2=88d_2 = 88 (from the equation of P2P_2)
  • βˆ₯nβˆ₯\|\mathbf{n}\| is the magnitude of the normal vector n\mathbf{n}.

First, calculate the magnitude of n\mathbf{n}:

βˆ₯nβˆ₯=22+32+(βˆ’6)2=4+9+36=49=7\|\mathbf{n}\| = \sqrt{2^2 + 3^2 + (-6)^2} = \sqrt{4 + 9 + 36} = \sqrt{49} = 7

Now, calculate the distance:

Distance=∣88βˆ’(βˆ’10)∣7=987=14\text{Distance} = \frac{|88 - (-10)|}{7} = \frac{98}{7} = 14

So, the minimum distance between the two planes is 14 units.

Part (b): Nearest Point on P2P_2 from Point (βˆ’2,0,1)(-2, 0, 1) on P1P_1

To find the nearest point on P2P_2, we project the point (βˆ’2,0,1)(-2, 0, 1) onto the plane P2P_2.

  1. Find the normal vector: n=⟨2,3,βˆ’6⟩\mathbf{n} = \langle 2, 3, -6 \rangle.

  2. Equation of the line passing through (βˆ’2,0,1)(-2, 0, 1) and along the direction of the normal vector is:

r(t)=(βˆ’2,0,1)+t⟨2,3,βˆ’6⟩=(βˆ’2+2t,3t,1βˆ’6t)\mathbf{r}(t) = (-2, 0, 1) + t \langle 2, 3, -6 \rangle = (-2 + 2t, 3t, 1 - 6t)

  1. Substitute these coordinates into the equation of plane P2P_2:

2(βˆ’2+2t)+3(3t)βˆ’6(1βˆ’6t)=882(-2 + 2t) + 3(3t) - 6(1 - 6t) = 88

  1. Simplify:

βˆ’4+4t+9tβˆ’6+36t=88-4 + 4t + 9t - 6 + 36t = 88

49tβˆ’10=8849t - 10 = 88

49t=98β‡’t=249t = 98 \quad \Rightarrow \quad t = 2

  1. Substitute t=2t = 2 back into the equation of the line to find the coordinates of the nearest point on P2P_2:

x=βˆ’2+2(2)=2x = -2 + 2(2) = 2 y=0+3(2)=6y = 0 + 3(2) = 6 z=1βˆ’6(2)=βˆ’11z = 1 - 6(2) = -11

So, the nearest point on P2P_2 is (2,6,βˆ’11)(2, 6, -11).

Summary:

  • The minimum distance between the two planes is 14 units.
  • The nearest point on P2P_2 to the point (βˆ’2,0,1)(-2, 0, 1) on P1P_1 is (2,6,βˆ’11)(2, 6, -11).

Do you want further details or have any questions?


Related Questions:

  1. How do you determine if two planes are parallel?
  2. What is the formula for the distance between a point and a plane?
  3. How can you find the distance between two skew lines?
  4. What is the geometrical significance of the normal vector of a plane?
  5. How do you find the angle between two intersecting planes?

Tip: Always ensure to calculate the magnitude of the normal vector carefully, as it is crucial for determining distances between planes.

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Math Problem Analysis

Mathematical Concepts

Geometry
Vectors
Planes

Formulas

Distance between two parallel planes
Equation of a line in 3D space

Theorems

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Suitable Grade Level

Advanced High School