∵O1O2⊥AB , ∴∠A O1O2 + ∠O1AB=90°,∵O1AB =∠C, 又∵∠D=∠ O1AB= ∠AO1O2 ,∴∠C+∠D=90°,∴O1C⊥AD.(3)成立.
超级试练试题库
© 2017-2019 超级试练试题库,All Rights Reserved.