Book 1, version 2022-08-08, section 11.2

[behrman]

page 370, figure 11.3: To be consistent, you would have a point at $\mathbf{a}_2$. Here are some ideas for improving the figure:

1. Show the column space as a plane, not the convex combination of the columns
2. Show $\mathbf{a}_1$, $\mathbf{a}_2$, $\mathbf{b}$, and $\mathbf{\hat{b}}$ as vectors, not just $\mathbf{b}$.
3. Have the projection line be different than the vector lines, and ideally have a right angle at where it meets the column space. This may entail having $\mathbf{b}$ above that subspace.

page 373, formula 11.28: The second = is only approximately equal.

[murphyk]

For fig 11.3, it would be great if you could make this for :)