Question

Answer 1

a) Ta có: \(a\perp AB,b\perp AB\Rightarrow a//b\)

b) Ta có: a//b

\(\Rightarrow\widehat{BDC}+\widehat{ACD}=180^0\)(trong cùng phía)

\(\Rightarrow\widehat{BDC}=180^0-50^0=130^0\)

\(\Rightarrow\widehat{BDC}=\widehat{C_2}=130^0\)(so le trong)

Answer 2

a) vì a⊥AB, b⊥AB⇒a//b

b) a//b⇒\(\widehat{ACD}+\widehat{BDC}=180^o\left(2.góc.trong.cùng.phía\right)\Rightarrow\widehat{BDC}=130^o\)

Ta có: \(\widehat{ACD}+\widehat{C_2}=180^o\left(2.góc.kề.bù\right)\Rightarrow\widehat{C_2}=130^o\)

Answer 3

a, Ta có: AB ⊥ a

               AB ⊥ b

\(\Rightarrow\) a//b (Quan hệ từ vuông góc đến song song)

b. Ta có: a//b (chứng minh trên)

\(\Rightarrow\) \(\widehat{ACD}+\widehat{BDC}=180^o\) (2 góc trong cùng phía)

Thay số: \(50^o+\widehat{BCD}=180^o\)

               \(\widehat{BCD}=180^o-50^o\)

                \(\widehat{BCD}=130^o\)

Ta có: \(\widehat{C}\)₂ = \(\widehat{BDC}=130^o\) (So le trong)