K
Khách

Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.

18 tháng 7 2018

27/12/2017 lúc 18:59

Ex1: Điền từ thích hợp vào chỗ trống

 This is Ba. He(1)......... a student.Every morning he(2).........up at 5.30.He(3).............. his teeth and takes a(4)............... then has breakfast at 6.15. He goes to school(5)........six thirty.His house is(6).............his house so he walks.The classes(7)............at 7.15 and finish at 11.15.In the afternoon he plays sports with his friend,Nam. They play badminton but now they(8).................soccer.In the evening he (9)......his homework and goes to(10).........at 9.30

Ex2:Cho dạng đúng của động từ trong ngoặc

1.My sister(have)...........classes from Monday to Friday

2.She(read)................a book in her room now

3.He(get)........................up at 6.00 every day?

4.There(not be)..............a big yard behind his classroom

27/12/2017 lúc 18:59

Ex1: Điền từ thích hợp vào chỗ trống

 This is Ba. He(1)......... a student.Every morning he(2).........up at 5.30.He(3).............. his teeth and takes a(4)............... then has breakfast at 6.15. He goes to school(5)........six thirty.His house is(6).............his house so he walks.The classes(7)............at 7.15 and finish at 11.15.In the afternoon he plays sports with his friend,Nam. They play badminton but now they(8).................soccer.In the evening he (9)......his homework and goes to(10).........at 9.30

Ex2:Cho dạng đúng của động từ trong ngoặc

1.My sister(have)...........classes from Monday to Friday

2.She(read)................a book in her room now

3.He(get)........................up at 6.00 every day?

4.There(not be)..............a big yard behind his classroom

27/12/2017 lúc 18:59

Ex1: Điền từ thích hợp vào chỗ trống

 This is Ba. He(1)......... a student.Every morning he(2).........up at 5.30.He(3).............. his teeth and takes a(4)............... then has breakfast at 6.15. He goes to school(5)........six thirty.His house is(6).............his house so he walks.The classes(7)............at 7.15 and finish at 11.15.In the afternoon he plays sports with his friend,Nam. They play badminton but now they(8).................soccer.In the evening he (9)......his homework and goes to(10).........at 9.30

Ex2:Cho dạng đúng của động từ trong ngoặc

1.My sister(have)...........classes from Monday to Friday

2.She(read)................a book in her room now

3.He(get)........................up at 6.00 every day?

4.There(not be)..............a big yard behind his classroom

Dễ quá đi

25 tháng 9 2021

Áp dụng HTL:

\(\left\{{}\begin{matrix}AH^2=BH\cdot HC\\AB^2=BH\cdot BC\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}BH=\dfrac{AH^2}{HC}=8\left(cm\right)\\AB^2=8\left(8+2\right)=80\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}BH=8\left(cm\right)\\AB=4\sqrt{5}\left(cm\right)\end{matrix}\right.\)

25 tháng 9 2021

undefined

\(\dfrac{1}{AH^2}=\dfrac{1}{AB^2}+\dfrac{1}{AC^2}\)

\(\Leftrightarrow\dfrac{1}{9}=\dfrac{1}{AB^2}+\dfrac{1}{25}\)

\(\Leftrightarrow\dfrac{1}{AB^2}=\dfrac{16}{225}\)

\(\Leftrightarrow AB=\dfrac{15}{4}\)

\(AH.BC=AB.AC\)

\(3.BC=\dfrac{15}{4}.5\)

\(BC=6,25\)

\(CH=\dfrac{AC^2}{BC}=4\)

=> BH = 6,25 - 4 = 2,25 

 

a: Ta có: \(AB=\dfrac{2}{3}AC\)

\(\Leftrightarrow\dfrac{HB}{HC}=\dfrac{4}{9}\)

\(\Leftrightarrow HB=\dfrac{4}{9}HC\)

Xét ΔABC vuông tại A có AH là đường cao ứng với cạnh huyền BC, ta được:

\(AH^2=HB\cdot HC\)

\(\Leftrightarrow HC^2\cdot\dfrac{4}{9}=144\)

\(\Leftrightarrow HC^2=324\)

\(\Leftrightarrow HC=18\left(cm\right)\)

\(\Leftrightarrow HB=8\left(cm\right)\)

\(\Leftrightarrow AB=\sqrt{8\cdot26}=4\sqrt{13}\left(cm\right)\)

5 tháng 8 2018

http://123link.pw/lv4a3hd

d) Xét ΔABC vuông tại A có 

\(\sin\widehat{B}=\dfrac{AC}{BC}=\dfrac{8}{10}=\dfrac{4}{5}\)

hay \(\widehat{B}\simeq53^0\)

Ta có: ΔABC vuông tại A(gt)

nên \(\widehat{B}+\widehat{C}=70^0\)(hai góc nhọn phụ nhau)

hay \(\widehat{C}=37^0\)

12 tháng 7 2021

Còn câu C thì sao ạ?