Challenge Problems for Chapter 6

Argue geometrically to prove that the following transformations are linear:
(a)
Rotation of the plane about the origin through angle .
(b)
Reflection of the plane about the line .
Think in terms of linearity diagrams.

What happens when you rotate two vectors first, then add them, versus adding the two vectors first, then rotating the sum?

The figure below illustrates the left side of the diagram. Vectors and are added in the domain, then the sum is rotated through angle .

The next figure illustrates what happens when vectors and are rotated through angle , then their images are added together.

Because the diagonal of a parallelogram rotates with the parallelogram, it is clear that

Find the matrix of the linear transformation which rotates every vector in counter clockwise about the axis when viewed from the positive axis through an angle of 30 and then reflects through the plane.

Click on the arrow to see answer.

Let be a linear transformation such that . Find .
Let be a non-zero vector in . Given any vector in , show there exists a linear transformation with .
Given in , define by for all in .
(a)
Show that is a linear transformation.
(b)
Show that every linear transformation arises in this way (i.e. for some in .)
Write for .

Bibliography

Some of these problems come from Chapter 5 of Ken Kuttler’s A First Course in Linear Algebra. (CC-BY)

Ken Kuttler, A First Course in Linear Algebra, Lyryx 2017, Open Edition, pp. 272–315.

Some of these problems come from the end of Chapter 7 of Keith Nicholson’s Linear Algebra with Applications. (CC-BY-NC-SA)

W. Keith Nicholson, Linear Algebra with Applications, Lyryx 2018, Open Edition, pp. 376–386.

2024-09-11 17:55:08