Question

Answer 1

a//b, a⊥AB⇒b⊥AB⇒\(\widehat{ABC}=90^o\)

a//b⇒\(\widehat{ADC}+\widehat{BCD}=180^o\Rightarrow\widehat{ADC}+110^o=180^o\Rightarrow\widehat{ADC}=70^o\)

Answer 2

Bài 13:

Vì a//b mà a⊥AB nên b⊥AB

Do đó \(\widehat{ABC}=90^0\)

Mà a//b nên \(\widehat{C}+\widehat{ADC}=180^0\) (trong cùng phía)

Vậy \(\widehat{ADC}=180^0-110^0=70^0\)