Nomor 4 cara nya gimana ya?

X dirotasi [0, 90°] lalu dicerminkan terhadap sumbu x menghasilkan Y
Misal
R = rotasi [0, 90°] = (cos 90° ... - sin 90°) = (0 ... -1)
................................... (sin 90° ..... cos 90°) .... (1 ... 0)

M = pencerminan terhadap sumbu x = (1 .... 0)
........................................................................ (0 .. -1)

(M o R) X = Y maka X = (M o R)^-1 Y ==> X = A Y
Jadi
A = (M o R)^-1

M o R = (1 ... 0) (0 ... -1) = (0 ... -1)
.............. (0 .. -1) (1 ..... 0) .. (-1 .. 0)

A = (M o R)^-1 = 1/(-1) (0 ... 1) = (0 ... -1)
...................................... (1 ... 0) .. (-1 ... 0)