a) sin a=0,8

Ta có: \(\sin^2a+\cos^2a=1\)

\(\Rightarrow\cos^2a=1-\sin^2a=1-0,8^2=0,36\)

\(\Rightarrow\orbr{\begin{cases}\cos a=0,6\\\cos a=-0,6\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}\tan a=\frac{4}{3}\\\tan a=\frac{-4}{3}\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}\cot a=\frac{3}{4}\\\cot a=\frac{-3}{4}\end{cases}}\)

\(\sin a=0,8\)

\(\sin^2a=1-\sin^2a=1\)

\(\cos^2a=1-\sin^2a=1-0,8^2=0,36\)

\(\Rightarrow\hept{\begin{cases}\cos a=0,6\\\cos a=-0,6\end{cases}}\)

\(\Rightarrow\hept{\begin{cases}\tan a=\frac{4}{3}\\\tan a=\frac{-4}{3}\end{cases}}\)

\(\Rightarrow\hept{\begin{cases}\cot a=\frac{3}{4}\\\cot a=\frac{-3}{4}\end{cases}}\)

Code : Breacker

Trả Lời : 

Google bạn nhé !!!!

Học tốt 

ĐKXĐ:  \(x>0\)

\(P=\left(\frac{1}{x+\sqrt{x}}-\frac{1}{\sqrt{x}+1}\right):\frac{\sqrt{x}}{x+2\sqrt{x}+1}\)

\(=\left(\frac{1}{\sqrt{x}\left(\sqrt{x}+1\right)}-\frac{\sqrt{x}}{\sqrt{x}\left(\sqrt{x}+1\right)}\right).\frac{\left(\sqrt{x}+1\right)^2}{\sqrt{x}}\)

\(=\frac{1-\sqrt{x}}{\sqrt{x}\left(\sqrt{x}+1\right)}.\frac{\left(\sqrt{x}+1\right)^2}{\sqrt{x}}\)

\(=\frac{\left(1-\sqrt{x}\right)\left(1+\sqrt{x}\right)}{x}\)

\(=\frac{1-x}{x}\)

mik ko bít

I don't now

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\(\Delta ABC\)là tam giác vuông. do \(\sqrt{AB^2+AC^2}=BC\)

a) tìm \(\widehat{C}\)

            \(sinC=\frac{AB}{BC}=\frac{10}{26}=\frac{5}{13}\)

             \(\Rightarrow\widehat{C}\approx23º\)

Tìm góc B: \(\widehat{B}=90º-\widehat{C}\approx90º-23º\approx67º\)

b) tìm AH

\(AH.BC=AB.AC\)

\(\Leftrightarrow AH.26=10.24\)

\(\Leftrightarrow AH=240:60=4cm\)

có j sai xót mong m.n bỏ qa

mik ko bít

I don't now

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mik ko bít

I don't now

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mik ko bít

I don't now

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A. Bài tập cơ bản:Viết lại các câu, bắt đầu bằng “ I wish”

   1. I don’t have to study.  

-   I wish ………I had to study……………………….……………

2. We had a lot of homework yesterday.

I wish ……………we hadn't had a lot of homework yesterday.………….

3. It rains. . 

  -   I wish …………it didn't rain…………………………….………………………..

4. It was very cold last night. .  

-   I wish ……………………it hadn't been ery cold last night.……….……..

5. They work slowly. .  

-   I wish ……………They didn't work slowly.………….…..…………

5. She doesn’t join in the trip.  .  

-   I wish ……………She joined in the trip.  .  ………………………….……

6. I am not good at English. . 

  -   I wish …………… I were good at English. .………….………

7. He studies badly.  .  

-   I wish …………… He didn't study badly.  .  ………………………….………………..

8. He doesn’t playing sports. . 

-   I wish …………………He  d playing sports. . …………………….…

9. I don’t have a computer.   

-   I wish …………I had a computer. …………………..………….………

10. Today isn’t a holiday.   

-   I wish ………………Today were a holiday……………………….…………