A = 1 nha

1. There is a good.............................of meat on the stall

A. kind             B. selection        C. type              D. stall

2. ....................he..................last semester?-Very well.

A. How/ studied       B. How did / studied  C. How does / study    D. How did /study

3. An speaks....................................

A. English perfect     B. English perfectly   C. perfectly English     D. perfected English

4. The dentist......................a cavity in Nam's tooth last Sunday.

A. pulled            B. drilled           C. Washed           D. filled

5. Liz never goes to school late and I.....................

A. didn't either        B. don't too         C. neither do         D. don't either

Choose the best answer (A, B, C or D) for each sentence below

1. There is a good.............................of meat on the stall

A. kind             B. selection        C. type              D. stall

2. ....................he..................last semester?-Very well.

A. How/ studied       B. How did / studied  C. How does / study    D. How did /study

3. An speaks....................................

A. English perfect     B. English perfectly   C. perfectly English     D. perfected English

4. The dentist......................a cavity in Nam's tooth last Sunday.

A. pulled            B. drilled           C. Washed           D. filled

5. Liz never goes to school late and I.....................

A. didn't either        B. don't too         C. neither do         D. don't either

Vì \(\Delta ABC\) vuông tại A \(\Rightarrow\widehat{A}=90^0\Leftrightarrow BC^2=AB^2+AC^2\) ( ĐL Pytago )

Vì \(\frac{AB}{AC}=\frac{8}{15}\Leftrightarrow\frac{AB}{8}=\frac{AC}{15}\Leftrightarrow\frac{AB^2}{8^2}=\frac{AC^2}{15^2}\). Áp dụng t/c dãy tỉ số bằng nhau

Ta có : \(\frac{AB^2}{8^2}=\frac{AC^2}{15^2}=\frac{AB^2+AC^2}{8^2+15^2}=\frac{BC^2}{64+225}=\frac{2061}{289}=9\)

\(\frac{AB^2}{8^2}=9\Leftrightarrow\sqrt{\frac{AB^2}{8^2}}=\sqrt{9}\Leftrightarrow\frac{AB}{8}=3\Leftrightarrow AB=3.8=24\left(cm\right)\)

\(\frac{AC^2}{15^2}=9\Leftrightarrow\sqrt{\frac{AC^2}{15^2}}=\sqrt{9}\Leftrightarrow\frac{AC}{15}=3\Leftrightarrow AC=15.3=45\left(cm\right)\)

Chu vi \(\Delta ABC=24+45+51=120\left(cm\right)\)

Diện tích \(\Delta ABC=\frac{a\times h}{2}=\frac{24\times45}{2}=\frac{1080}{2}=540\left(cm\right)\)

Vẽ hình tam giác có hai cạnh góc vuông \(\sqrt{a}\)và \(\sqrt{b}\), độ dài cạnh huyền là c.

Áp dụng định lý Pytago ta có: \(\left(\sqrt{a}\right)^2+\left(\sqrt{b}\right)^2=a+b=c^2\)

\(\Rightarrow c=\sqrt{a+b}\)

Theo bất đẳng thức tam giác thì: \(\sqrt{a}+\sqrt{b}>c=\sqrt{a+b}\left(đpcm\right)\)

Coffee Teaa . Tớ là Akai#4760

Bạn tham khảo link này:

https://olm.vn/hoi-dap/detail/58559568033.html

Chúc bạn học tốt

Forever 

cảm ơn bn nha!!!