Conclusion:Whena segmentis reflectedin the -axis,the imagesegmenthas the samelengthas the
originalsegment.This is the meaningof isometry. You can see that a similarargumentwouldapplyto re-
flectionin any line.
MatrixMultiplication
Multiplyingmatricesis a little morecomplicatedthan addition.Matrixmultiplicationis sometimescalleda
“row-by-column”operation.Let’s beginwith examples.
Let and
-by- -by- -by--by- -by- -by--by- -by- -by-Notice:
- The productis a matrix.
- The numberof rowsin the productmatrixis the sameas the numberof rowsin the left matrixbeing
multiplied. - The numberof columnsin the productmatrixis the sameas the numberof columnsin the right matrix
beingmultiplied. - The numberof columnsin the left matrixis the sameas the numberof rowsin the right matrix.