Matrices Flashcards
multiplying by the identity matrix
multiplying by 1
multiplying by the null/zero matrix
multiplying by 0
order/dimension of a matrix
the number of rows/columns
you can only add matrices if they have…
the same order
AB != BA
matrix multiplication is not commutative
a(bc) = (ab)c
Associative Property of Multiplication
a(b+c) = ab + ac
Distributive
conformable
mxn order can be multiplied by nxp order giving a matrix of order mxp
a stretch parallel to the x-axis with scale factor k
K 0
0 1
A stretch parallel to the y-axis with scale factor k
1 0
0 K
A enlargement centre of origin with scale factor k
K 0
0 K
A rotation 90 anti-clockwise about the origin
0 -1
1 0
A rotation 90 clockwise about the origin
0 1
-1 0
leading diagonal rule rotation matrices
the elements in the leading diagonal are the exact same
the elements in the opposite diagonal are the same but with opposite signs
A rotation of any angle anticlockwise
cosθ -sinθ
sinθ cosθ
reflection in the x-axis
1 0
0 -1
reflection in the y-axis
-1 0
0 1
reflection in the line y=x
0 1
1 0
reflection in the line y=-x
0 -1
-1 0
Shear
a transformation in which all the point are translated parallel to a particular line by a factor which is proportional to the distance of the point from a shear line
shear parallel to the x-axis
1 K
0 1
shear parallel to the y-axis
1 0
K 1