Math Problem Statement

Do it

Consider the following parametric representation of a plane: r = (2, 1, 4) + s(1, -2, 1) + t(1, -4, 3). Enter vectors r_0 and n such that (r - r_0) • n = 0 is the point-normal form of the plane r. Now enter the scalar (Cartesian) form of the equation.

Solution

The image shows a parametric equation of a plane:

r=(2,1,4)+s(1,2,1)+t(1,4,3)\mathbf{r} = (2, 1, 4) + s(1, -2, 1) + t(1, -4, 3)

You are tasked with converting this parametric form to the scalar (Cartesian) form of the plane's equation. You've already identified the point r0=(2,1,4)\mathbf{r_0} = (2, 1, 4) and the normal vector n=(2,2,2)\mathbf{n} = (-2, -2, -2).

To convert the parametric form to scalar form, the equation of the plane can be written as:

n(rr0)=0\mathbf{n} \cdot (\mathbf{r} - \mathbf{r_0}) = 0

Given n=(2,2,2)\mathbf{n} = (-2, -2, -2) and r0=(2,1,4)\mathbf{r_0} = (2, 1, 4), we substitute into the general form of the plane equation:

2(x2)2(y1)2(z4)=0-2(x - 2) - 2(y - 1) - 2(z - 4) = 0

Simplifying:

2x+42y+22z+8=0-2x + 4 - 2y + 2 - 2z + 8 = 0 2x2y2z+14=0-2x - 2y - 2z + 14 = 0 Dividing the entire equation by 2-2:

x+y+z7=0x + y + z - 7 = 0

Thus, the scalar form of the equation is:

x+y+z=7x + y + z = 7

Would you like further details or have any questions? Here are some related questions to consider:

  1. How is the normal vector to a plane determined from the parametric form?
  2. Why does the dot product of the normal vector and a point on the plane yield zero?
  3. What is the geometric meaning of the point-normal form of a plane?
  4. How can parametric equations be used in vector calculus?
  5. How does this method generalize to finding the equation of a plane in 3D space?

Tip: When converting parametric forms to scalar forms, always check that the vector used as the normal is perpendicular to both direction vectors in the parametric equation.

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Math Problem Analysis

Mathematical Concepts

Geometry
Vector Calculus
Planes in 3D Space

Formulas

Point-normal form of a plane: (r - r_0) • n = 0
Scalar (Cartesian) form of a plane: ax + by + cz = d

Theorems

Dot product theorem for planes
Point-normal form of a plane

Suitable Grade Level

Grades 11-12