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Planes in Space

A point and a normal vector determine a plane; finding its equation from three points or from other geometric information.

Active Calculus Multivariable, Planes in Space

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6 exercises

Activity 9.7.2

  1. Write a scalar equation of the plane p1p_1 passing through the point (0,2,4)(0, 2, 4) and perpendicular to the vector n⃗=⟨2,−1,1⟩\vn=\langle 2, -1, 1\rangle.

  2. Is the point (2,0,2)(2, 0, 2) on the plane p1p_1?

  3. Write a scalar equation of the plane p2p_2 that is parallel to p1p_1 and passes through the point (3,0,4)(3, 0, 4).

  4. Give parametric equations for the line L\mathcal{L} passing through the point (2,0,2)(2,0,2) and perpendicular to the plane p3p_3 described by the equation x+2y−2z=7x+2y-2z = 7.

  5. Find the point at which L\mathcal{L} intersects p3p_3.

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Activity 9.7.3

Let P0=(1,2,−1)P_0 = (1,2,-1), P1=(1,0,−1)P_1 = (1, 0 ,-1), and P2=(0,1,3)P_2 = (0,1,3) and let pp be the plane containing P0P_0, P1P_1, and P2P_2.

  1. Determine the components of the vectors P0P1→\overrightarrow{P_0P_1} and P0P2→\overrightarrow{P_0P_2}.

  2. Find a normal vector n⃗\vn to pp.

  3. Find a scalar equation of pp.

  4. Consider a second plane qq with scalar equation −3(x−1)+4(y+3)+2(z−5)=0-3(x-1) + 4(y+3) + 2(z-5)=0. Find two different points on qq as well as a vector m⃗\vm that is normal to qq.

  5. What is the angle between planes pp and qq?

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Exercise 28

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Exercise 29

This exercise explores key relationships between a pair of planes. Consider the following two planes: one with scalar equation 4x−5y+z=−24x - 5y + z = -2, and the other which passes through the points (1,1,1)(1,1,1), (0,1,−1)(0,1,-1), and (4,2,−1)(4, 2, -1).

  1. Find a vector normal to the first plane.

  2. Find a scalar equation for the second plane.

  3. Find the angle between the planes, where the angle between them is defined by the angle between their respective normal vectors.

  4. …

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Exercise 30

  1. Find the plane that goes through the points (1,2,3)(1,2,3), (4,5,6)(4,5,6), and (7,8,9)(7,8,9) or explain why there is not one plane that satisfies this condition.

  2. Find all planes in R3\mathbb{R}^3 whose line of intersection with the xzxz-plane is given by πx+ez=5\pi x +e z=\sqrt{5}.

  3. Give two vectors that are in the plane given by 3x+4y=6z−203x+4y=6z-20 and are orthogonal to each other.

  4. Give the equations of two planes that make a 90∘90^\circ angle with 3x+4y=6z−203x+4y=6z-20 and have an angle of 90∘90^\circ between them as well.

  5. Give the p…

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Exercise 39

In this problem, we explore how we can use what we know about vectors and projections to find the distance from a point to a plane.

Let pp be the plane with equation z=−4x+3y+4z=-4x+3y+4, and let Q=(4,−1,8)Q = (4,-1,8).

  1. Show that QQ does not lie in the plane pp.

  2. Find a normal vector n⃗\vn to the plane pp.

  3. Find the coordinates of a point PP in pp.

  4. Find the components of PQ→\overrightarrow{PQ}. Draw a picture to illustrate the objects found so far.

  5. Explain why ∣compn⃗PQ→∣|\comp_{\vn} \overrightarrow{PQ}| gives the di…

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Adapted from Active Calculus Multivariable © 2013–2026 Nicholas Long, Mitchel T. Keller, and Steven Schlicker. Licensed under CC BY-SA 4.0. Source: Active Calculus Multivariable. Imported at revision 692c03c.