25.08.2021 Views

082-Engineering-Mathematics-Anthony-Croft-Robert-Davison-Martin-Hargreaves-James-Flint-Edisi-5-2017

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

270 Chapter 8 Matrix algebra

V new

=

So,

⎛ ⎞

1

r new

= ⎝−2⎠

1

⎛ ⎞ ⎛ ⎞ ⎛ ⎞

10 00 1 1

⎜00−10

⎟ ⎜1

⎝01 00⎠

⎝2⎠ = ⎜−2

⎝ 1⎠

00 01 1 1

Example8.13 Translate the vector

⎛ ⎞

1

r = ⎝3⎠

2

by

⎛ ⎞

1

⎝2⎠

3

and then rotate by 90 ◦ about theyaxis.

⎛ ⎞

⎛ ⎞ 1

1

Solution r old

= ⎝3⎠ V old

= ⎜3

⎝2⎠

2

1

To translate r old

, weform

⎛ ⎞

1001

Trans(1,2,3) = ⎜0102

⎝0013⎠

0001

Then

⎛ ⎞ ⎛ ⎞ ⎛ ⎞

1001 1 2

Trans(1,2,3)V old

= ⎜0102

⎟ ⎜3

⎝0013⎠

⎝2⎠ = ⎜5

⎝5⎠

0001 1 1

To rotate by 90 ◦ about theyaxis we require

⎞ ⎛ ⎞

cos90 ◦ 0 sin90 ◦ 0 0010

Rot(y,90 ◦ ) = ⎜ 0 1 0 0

⎝−sin90 ◦ 0 cos90 ◦ 0⎠ = ⎜ 0100

⎝−1000⎠

0 0 0 1 0001

⎛ ⎞

2

The vector ⎜5

⎝5⎠ ispremultiplied by thismatrix togive

1

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!