∴DG∥BC (same angle, two parallel straight lines)

∴∠∠ 1 =∠ DCB (two straight lines are parallel with equal internal angles)

∵CD⊥AB,EF⊥AB

∴∠CDE=90，∠FEB=90

∴EF∥DC

∴∠2=∠DCB (two straight lines are parallel and have the same included angle)

∴∠ 1=∠2