Recall than an angle is acute if it's between $0$ and $\frac{\pi}{2}$ radians, right if it equals $\frac{\pi}{2}$ radians, and obtuse if is between $\frac{\pi}{2}$ and $\pi$ radians. For each angle below enter R if it is a right angle, A if it's an acute angle, and O (upper case o, not the digit $0$) if it is an obtuse angle.

$90^\circ$
$60^\circ$
$130^\circ$
$1\hbox{rad}$
$2\hbox{rad}$
$\frac{\pi}{2}\hbox{rad}$