Question Number 33158 by Rio Mike last updated on 11/Apr/18
$${the}\:{matrice}\:{which}\:{comes}\:{from} \\ $$$${the}\:{transformation}\:{matrix}\: \\ $$$$\:\begin{pmatrix}{{cos}\theta\:\:\:\:\:\:\:\:\:−{sin}\theta}\\{{sin}\:\theta\:\:\:\:\:\:\:\:\:\:\:\:\:\:{cos}\theta}\end{pmatrix} \\ $$$${at}\:\mathrm{90}°\:{is}? \\ $$
Commented by Joel578 last updated on 11/Apr/18
$$\mathrm{You}\:\mathrm{just}\:\mathrm{substitute}\:\theta\:=\:\mathrm{90}°\:\mathrm{into}\:\mathrm{the}\:\mathrm{matrice} \\ $$
Commented by prof Abdo imad last updated on 15/Apr/18
$${this}\:{is}\:{a}\:{matrice}\:{of}\:{rotation}\:{at}\:{ev}.{V}_{\mathrm{2}} \:{and}\:{for} \\ $$$$\theta\:=\frac{\pi}{\mathrm{2}}\:{the}\:{matrice}\:{become}\:\:\begin{pmatrix}{\mathrm{0}\:\:\:\:\:−\mathrm{1}}\\{\mathrm{1}\:\:\:\:\:\:\:\:\mathrm{0}}\end{pmatrix} \\ $$