如图,如在平面上将△ABC绕B点旋转到△A’BC’的位置时,AA’∥BC,∠ABC=70°,则∠CBC’为________度.

问题描述:

如图,如在平面上将△ABC绕B点旋转到△A’BC’的位置时,AA’∥BC,∠ABC=70°,则∠CBC’为________度.

∠CBC'=∠ABA'
=∠A'BC-∠ABC
=(180-∠BA'A)-∠ABC
=(180-∠A'AB)-∠ABC
=(180-∠ABC)-∠ABC
=180-70-70
=40