venhance / egmo-book-errata Goto Github PK

The errata in TeX format should be synchronized to the one in PDF format.

Creating a separate issue so I can track these. From @annnagatsuki

Additional ToDos:

Reword p. 126: “It is important that x + y + z = 1 when doing calculations with displacement vectors” should be “… x + y + z = 0 ….”
Solution to Example 7.30: an abuse of notation in defining the coordinates of point P.
There is a definition of two circles being orthogonal but no definition of a circle being orthogonal to another circle.
There is no definition of the complete quadrilateral being cyclic such as the one in tr011ey.
p. 274: isogonal with respect to \angle{BAC}'' is undefined in this book. Solution 11.11: the angle bisector''.
Solution 10.30: This logic of the first sentence seems very strange to me. The analogous calculation does not imply the second expression and the second one itself will not give the third one. Even if the subject of the relative clause should be interpreted as “the analogous calculation,” which would make some sense to me, the former issue still does not resolve at all. Above all, this introduction might imply that “directed SAS” is going to be used to show the similarity, even though we are going to show accordingly with the definition itself by using cyclic permutations of indices.

It is important that x + y + z = 1 when doing calculations with displacement vectors. (p. 126)

Easily achievable alternatives:

1. change "x + y + z = 1" to "x + y + z = 0".
2. delete "however" in the preceding sentence.

Things to be considered:

• The word ‘however’ in “… since x + y + z = 1. As a result, however: It is important that x + y + z = 1 when doing calculations with displacement vectors” implies that two topics are somewhat adversative (opposite). Since the former topic is the coordinates of points, the latter topic should be the displacement vectors, and its focus should also be the important fact: x + y + z = 1, which is the same as the former one!
• Right after this sentence in the same page, x + y + z = 0 is called as the sum of the coordinates in a displacement vector. So is the proof of Theorem 7.16, and Theorem 7.15 and 7.24 where x + y + z = 1 is emphasized are only for points, not for displacement vectors.
• Motivation for using pseudo-displacement vector is explained as “we only need one of the displacement vectors to be zero for the entire product to be zero,” which implies that the convenience of pseudo-ones is substantiated by saying x + y + z = 0 is important in displacement vectors.