a) Xét \(\Delta BKC\) và \(\Delta CHB\) có:

BC (chung

\(\widehat{BKC}=\widehat{CHB}=90^0\)

\(\widehat{KBC}=\widehat{HCB}\) (\(\Delta ABC\) cân tại A)

Do đó: \(\Delta BKC=\Delta CHB\left(ch-gn\right)\)

=> BH = CK (hai cạnh tương ứng)

b) Ta có: BH là đường cao \(\Delta ABC\)

CK là đường cao \(\Delta ABC\)

mà BH cắt CK tại M

=> M là trực tâm

=> AM là đường cao \(\Delta ABC\)

AM cắt BC tại N

mà \(\Delta ABC\) cân tại A

=> BN = NC

Xét \(\Delta BMN\) và \(\Delta CMN\) có:

MN (chung)

\(\widehat{MNB}=\widehat{MNC}=90^0\)

BM = NC (cmt)

Do đó: \(\Delta BMN=\Delta CMN\left(c-g-c\right)\)

=> BM = CM (hai cạnh tương ứng)

=> \(\Delta BMN\) cân tại M

mik chỉ bt thế thui

1. My father is watching television at the moment

2. We are walking to school right now

3. They are studying Geography at this time

4. He is listening to the radio now

5. Nam and Nga are having lunch at preset

6. Miss Lien is playing the piano

7. The girls are eating breakfast at the canteen now

8. I am doing my homework at present

You looked exhausted. I think you’ve ______ more than you can handle.

A. turned on

B. taken up

C. turned up 

D. taken on