Linear Algebra and Its Applications (5th Edition)

Published by Pearson
ISBN 10: 032198238X
ISBN 13: 978-0-32198-238-4

Chapter 2 - Matrix Algebra - 2.7 Exercises - Page 147: 14

Answer

See solution

Work Step by Step

Transformation matrix is: $\left[\begin{array}{ccc}1 / 2 & -\sqrt{3} / 2 & 3+4 \sqrt{3} \\ \sqrt{3} / 2 & 1 / 2 & 4-3 \sqrt{3} \\ 0 & 0 & 1\end{array}\right]$ Notice that this matrix has a form of $\left[\begin{array}{cc}A & p \\ 0^{T} & 1\end{array}\right],$ where $A=\left[\begin{array}{cc}1 / 2 & -\sqrt{3} / 2 \\ \sqrt{3} / 2 & 1 / 2\end{array}\right]$ and $p=\left[\begin{array}{l}3+4 \sqrt{3} \\ 4-3 \sqrt{3}\end{array}\right]$ We know that the starting matrix can be written as $\left[\begin{array}{cc}I & p \\ 0^{T} & 1\end{array}\right]\left[\begin{array}{cc}A & 0 \\ 0^{T} & 1\end{array}\right]$ This is a composition of a linear transformation in $\mathbb{R}^{2}$ and a translation for a vector $p$ Matrix $A$ is a rotation of $60^{\circ}=\frac{\pi}{3}$ about the origin in $\mathbb{R}^{2}$. So, the transformation in exercise 7 is a composition of a rotation about the origin and a translation by vector $p=\left[\begin{array}{l}3+4 \sqrt{3} \\ 4-3 \sqrt{3}\end{array}\right]$
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.