Find the 3 × 3 matrix that produces the described transformation, using homogeneous coordinates.
-Reflect through the x-axis
A)
$\left[ \begin{array} { r r r r } - 1 & 0 & 0 \ 0 & 1 & 0 \ 0 & 0 & 1 \end{array} \right]$

B)
$\left[ \begin{array} { r r r } 1 & 0 & 0 \ 0 & - 1 & 0 \ 0 & 0 & 1 \end{array} \right]$

C)
$\left[ \begin{array} { r r r } - 1 & 0 & 0 \ 0 & - 1 & 0 \ 0 & 0 & 1 \end{array} \right]$

D)

$\left[ \begin{array} { l l l } 1 & 0 & 0 \ 0 & 1 & 0 \ 0 & 0 & 1 \end{array} \right]$

Question

Find the 3 × 3 matrix that produces the described transformation, using homogeneous coordinates.
-Reflect through the x-axis 
A)
$\left[ \begin{array} { r r r r } - 1 & 0 & 0 \ 0 & 1 & 0 \ 0 & 0 & 1 \end{array} \right]$

B)
$\left[ \begin{array} { r r r } 1 & 0 & 0 \ 0 & - 1 & 0 \ 0 & 0 & 1 \end{array} \right]$

C)
$\left[ \begin{array} { r r r } - 1 & 0 & 0 \ 0 & - 1 & 0 \ 0 & 0 & 1 \end{array} \right]$

D)

$\left[ \begin{array} { l l l } 1 & 0 & 0 \ 0 & 1 & 0 \ 0 & 0 & 1 \end{array} \right]$

Quizplus · Accepted Answer

Reflecting through the x-axis in homogeneous coordinates involves negating the y-coordinate while leaving the x-coordinate and the homogeneous coordinate unchanged, which is exactly what option B does.

Find the 3 × 3 Matrix That Produces the Described [−100010001]\left[ \begin{array} { r r r r } - 1 & 0 & 0 \\ 0 & 1 & 0 \\ 0 & 0 & 1 \end{array} \right]​−100​010​001​​

Find the 3 × 3 Matrix That Produces the Described $\left[ \begin{array} { r r r r } - 1 & 0 & 0 \\ 0 & 1 & 0 \\ 0 & 0 & 1 \end{array} \right]$