ko cíu nỗi

chiều nay tui giải đc hơm:)

động vật

dong vat

súc vật

\(=\dfrac{1}{2}-\dfrac{1}{2}cos\dfrac{2\pi}{9}+\dfrac{1}{2}-\dfrac{1}{2}cos\dfrac{4\pi}{9}+\dfrac{1}{2}cos\dfrac{\pi}{9}-\dfrac{1}{2}cos\dfrac{3\pi}{9}\)

\(=1-\dfrac{1}{2}\left(cos\dfrac{2\pi}{9}+cos\dfrac{4\pi}{9}\right)+\dfrac{1}{2}cos\dfrac{\pi}{9}-\dfrac{1}{4}\)

\(=\dfrac{3}{4}-cos\dfrac{\pi}{9}.cos\dfrac{3\pi}{9}+\dfrac{1}{2}cos\dfrac{\pi}{9}\)

\(=\dfrac{3}{4}-\dfrac{1}{2}cos\dfrac{\pi}{9}+\dfrac{1}{2}cos\dfrac{\pi}{9}\)

\(=\dfrac{3}{4}\)

bài nào ạ?

the

the

the

em chưa học đến cái đó xin lỗi chị nhìu nha ;-;

6. pay you back on Saturday.

7. I close the door?

8. have a drink?

9. you help me with math problem?

10. stop making noise, please? the baby is sleeping.