2∠1+∠C-∠B
∵△BAD和△DAC是Rt△
∴∠BAD=180°-30°-90°=60°
∠DAC=180°-50°-90°=40°
∵三角形内角和是180°
∴ ∠B+∠C+∠BAC=180°
∴∠BAC=180°-(∠B+∠C)=180°-(30°+50°)=100°
∵AE平分∠BAC
∴∠BAE=∠EAC=1/2 ∠BAC=1/2 x 100°=50°
∵∠BAD=∠1+∠BAE
∴∠1=∠BAD-∠BAE=60°-50°=10°
∠B-∠C=50°-30°=20°
∴2 ∠1=∠C-∠B