∵AR和BR分别为角平分线
∴∠BAR=1/2∠BAC,∠ABR=1/2∠ABC
∵∠C =90°
∴∠BAC +∠ACB =90°
∴∠BAR+∠ABR=1/2*90°=45°
∴∠ARE =∠BAR+∠ABR=45°