D - C - A - D - A - B - C - C

(O) có \(\widehat{BIC}\) là góc có đỉnh ở bên trong đường tròn chắn \(\stackrel\frown{BC},\stackrel\frown{AD}\) nên \(\widehat{BIC}=\dfrac{Sđ\stackrel\frown{BC}+Sđ\stackrel\frown{AD}}{2}\)(1)

\(\widehat{BCD}\) là góc nội tiếp chắn \(\stackrel\frown{BD}\) nên \(\widehat{BCD}=\dfrac{Sđ\stackrel\frown{BD}}{2}=\dfrac{Sđ\stackrel\frown{AB}+Sđ\stackrel\frown{AD}}{2}\) (2)

(O) có AB, BC là 2 dây bằng nhau nên \(\stackrel\frown{AC}=\stackrel\frown{BC}\Rightarrow Sđ\stackrel\frown{AC}=Sđ\stackrel\frown{BC}\). Do đó từ (1) và (2) => \(\widehat{BCD}=\widehat{BIC}=70^0\)

BC=CD nên \(\Delta BCD\) cân tại C \(\Rightarrow\widehat{CBD}=\widehat{CDB}=\dfrac{180^0-\widehat{BCD}}{2}=\dfrac{180^0-70^0}{2}=55^0\)

\(\widehat{CID}=180^0-\widehat{BIC}=180^0-70^0=110^0\)

\(\Delta ICD\) có \(\widehat{ICD}=180^0-\widehat{CID}-\widehat{IDC}=180^0-110^0-55^0=15^0\)

\(\widehat{ACD}=\widehat{ICD}=15^0\)

b) 

a) \(\sqrt{2}x+1=7-x\Leftrightarrow\left(\sqrt{2}+1\right)x=6\Leftrightarrow x=\dfrac{6}{\sqrt{2}+1}=-6+6\sqrt{2}\)

b) \(\left\{{}\begin{matrix}2x+3y=2\\x-y=\dfrac{1}{6}\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}2x+3y=2\\3x-3y=\dfrac{1}{2}\end{matrix}\right.\Leftrightarrow}\left\{{}\begin{matrix}5x=\dfrac{5}{2}\\x-y=\dfrac{1}{6}\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{1}{2}\\y=x-\dfrac{1}{6}\end{matrix}\right.\Leftrightarrow}\left\{{}\begin{matrix}x=\dfrac{1}{2}\\y=\dfrac{1}{3}\end{matrix}\right.\)

There used to be servants.

People didn't use electricity.

People used to eat candies.

People didn't use to work and play games on computers.

33. They don't usually drink beer.

→ They do not get___used to drinking beer_____.

34. They say people built the school in 1990.

→ The school is_____said to have been built in 1990____.

35. The boy looks very handsome. He has just come back from Europe.

--->The boy who has just__come back from Europe looks very handsome____.

36. He cannot speak English, but he chooses to live in Australia.

--->Despite his_____unability to speak English, he chooses to live in Australia____.

25. The (volcano)__volcanic___eruption caused a lot of bad effects.

26. A (disaster)____disastrious__eruption occurred here last night.

27. They said "good bye" to each other just because of some minor (understand)__misunderstanding___.

28. The car is a complete write off. It is quite (repair)___unrepairable___.

29. He is an (experience)_____inexperienced___doctor who just graduated from the medical school last year.

30. The American boy spoke Vietnamese (nature)__unaturally____,but we all encouraged him to go on with his impressive speech.

ui xong Viet qua làm đồ thị đó à :))