M 311 Spring 2004 HOMEWORK SUMMARY REPORT Chapter number: 1 Section number: 2 Exercise number: 14 Number of papers received: 2 Reviewing committee: epsilon List all participating committee members: c-glaser, j-bosshard Author(s) of paper(s) chosen for publication: [James Macfarlane and reviewers' alternative] Comments: James's proof is essentially correct, while [the other] made a logical error by setting theta equal to zero. However, we believe an alternate solution presented below more closely follows the spirit of vector calculus: If r represents the displacement vector from the origin to any arbitrary point in the plane, and n is any vector normal to the plane, then r dotted with the unit normal vector (n/|n|) is the scalar projection of r onto the unit normal vector, which is the distance from the origin to the plane. Since it is stated that |n| = 1, by simplification, r dot n is the distance from the origin to the plane. And by Theorem 2, r dot n is d. Thus, d is the distance from the origin to the plane. INSTRUCTOR'S COMMENT: I think that James's trig-based argument is also worth displaying.