Question

[Nguyen Phuc Gia Han]

Giúp mình nhoa

Answer 1

[Aki Tsuki]

a) Ta có: AB \(\perp\) BC ; CD \(\perp\) BC

\(\Rightarrow\) AB // CD

b)

+)Ta có: \(\widehat{D_1}\) + \(\widehat{D_2}\) = 180^o ( hai góc kề bù)

hay 130^o + \(\widehat{D_2}\) = 180^o

\(\Rightarrow\) \(\widehat{D_2}\) = 180^o - 130^o = 50^o

+) Kẻ Ex // AB :

B C D E 1 2 A 50* 130*

Vì Ex // AB nên:

\(\widehat{A}\) = \(\widehat{E_1}\) = 50^o (cặp góc so le trong) (1)

Ta có : Ex // AB ; CD // AB

\(\Rightarrow\) Ex // CD

Vì Ex // CD nên :

\(\widehat{E_2}\) = \(\widehat{D_2}\) = 50^o (2)

Từ (1) và (2) \(\Rightarrow\) \(\widehat{AED}\) = \(\widehat{E_1}\) + \(\widehat{E_2}\)

hay \(\widehat{AED}\) = 50^o + 50^o

= 100^o

Answer 2

[Nguyễn Huy Tú]

A B C 1 D 2 I E 1 2 1 3

Giải:

a) Vì AB _|_ BC, CD _|_ BC nên suy ra AB // CD

b) Kẻ AI // AB

\(\Rightarrow\widehat{A_1}=\widehat{E_1}=50^o\) ( so le trong )

Ta có: \(\widehat{D_1}+\widehat{D_2}=180^o\) ( kề bù )

\(\Rightarrow130^o+\widehat{D_2}=180^o\)

\(\Rightarrow\widehat{D_2}=50^o\)

Vì AI // AB, AB // CD nên suy ra AI // CD

\(\Rightarrow\widehat{D_2}=\widehat{E_2}=50^o\) ( so le trong )

Mà \(\widehat{E_1}+\widehat{E_2}=\widehat{AED}\)

\(\Rightarrow\widehat{AED}=50^o+50^o=100^o\)

Vậy a) AB // CD

b) \(\widehat{D_2}=50^o,\widehat{AED}=100^o\)