hình bé quá

sin 65⁰=cos 35⁰
\(cos70^0=sin30^0\)
\(tan80^0=cot20^0\)
\(cot68^0=tan32^0\)

Ko nhìn chữ bn ơi, bn cho to hình một tý

\(3,\\ a,\dfrac{\left(1+\sqrt{x}\right)^2-4\sqrt{x}}{1-\sqrt{x}}\\ =\dfrac{\sqrt{x}-2\sqrt{x}+1}{1-\sqrt{x}}=\dfrac{\left(1-\sqrt{x}\right)^2}{1-\sqrt{x}}=1-\sqrt{x}=1-\sqrt{2}\)

\(b,\dfrac{\left(\sqrt{x}-\sqrt{y}\right)^2+4\sqrt{xy}}{1+\sqrt{xy}}\\ =\dfrac{x+2\sqrt{xy}+y}{1+\sqrt{xy}}=\dfrac{\left(\sqrt{x}+\sqrt{y}\right)^2}{1+\sqrt{xy}}\\ =\dfrac{\left(\sqrt{2}+\sqrt{3}\right)^2}{1+\sqrt{6}}=\dfrac{5+2\sqrt{6}}{1+\sqrt{6}}\\ =\dfrac{\left(5+2\sqrt{6}\right)\left(\sqrt{6}-1\right)}{5}\\ =\dfrac{3\sqrt{6}+7}{5}\)

bài 1

\(\widehat{B}=90-\widehat{C}=90-30=60\)

\(sinC=\dfrac{AB}{BC}\Rightarrow BC=\dfrac{AB}{sinC}=\dfrac{30}{sin30}=60\)

áp dụng pytago vào \(\Delta ABC\)

\(AC=\sqrt{BC^2-AB^2}\)=\(\sqrt{60^2-30^2}\)=\(30\sqrt{3}\)=51,96

bài 2

\(\widehat{B}=90-\widehat{C}=90-30=60\)

\(sinC=\dfrac{AB}{BC}\Rightarrow AB=sinC.BC=sin30.5=2,5\)

áp 

 

áp dụng pytago vào \(\Delta ABC\)

\(AC=\sqrt{BC^2-AB^2}=\sqrt{5^2-2,5^2}\)=4,33

bài 3

\(\widehat{E}=90-\widehat{F}=90-47=43\)

\(sinF=\dfrac{ED}{EF}\Rightarrow EF=\dfrac{ED}{sinF}=\dfrac{9}{sin47}=12,31\)

áp dụng pytago vào \(\Delta DEF\)

\(DF=\sqrt{EF^2-ED^2}=\sqrt{12,31^2-9^2}\)=8,4

bài 4

áp dụng pytago vào \(\Delta ABC\)

\(AB=\sqrt{BC^2-AC^2}=\sqrt{32^2-27^2}=17,18\)

\(sinB=\dfrac{AC}{BC}=\dfrac{27}{32}\Rightarrow\widehat{B}=57\)

\(\widehat{C}=90-\widehat{B}=90-57=33\)

My family consists of 4 people. There are my husband, my two little son, and I. My husband is forty-three years old, and he works as an engineer. I am a doctor. my first son is a policeman, and the second one is still a student in primary school. We all have a busy lives in day. However in the evening after dinner, we sit together in the living-room talking, sometimes watching a funny movie. Then my sons go to their own rooms. On weekend, and with spare time, my family often went on to play with parents, it is very meaningful and fun. We love each other very much and expect to live together under the same roof forever. I feel very happy to be alive in this family.

My family consists of 4 people. There are my husband, my two little son, and I. My husband is forty-three years old, and he works as an engineer. I am a doctor. my first son is a policeman, and the second one is still a student in primary school. We all have a busy lives in day. However in the evening after dinner, we sit together in the living-room talking, sometimes watching a funny movie. Then my sons go to their own rooms. On weekend, and with spare time, my family often went on to play with parents, it is very meaningful and fun. We love each other very much and expect to live together under the same roof forever. I feel very happy to be alive in this family.

Hi everybody, my name is ** and today, I'd to tell you about my day. I ensure that everybody is wondering a lot about my day, yeah? Now, you can know it. My day starts at 5 o'clock when I get up. Then I brush my teeth as well as get dressed. I get up early so as to learn by heart my lessons at school since the previous night, I just did the exercises, I didn't learn by heart my lessons because I realize that if we learn by heart something at night, we can't remember it for a long time but when we study at early morning, it really works. I do and I have a good memory now. I find it hard to forget my lessons. It's fabulous! Then I carry on my progress until 6.15 a.m. I stop studying to have a rest and have breakfast with my family and we finish by 6.45 a.m. Afterwards, I go to my extra class which starts at 7 and don't come home until 8.30 a.m. Next, my mother picks me up at my extra class and drives me home. She lets me relax for about 15 minutes so that I won't feel so confused and tired. You can see that my mother is very easy-going as she never makes me to study a lot as well as puts pressure on me. She often tells me that I should study in a comfortable way and shouldn't importanize the scores so much and she emphasizes that my knowledge is the most important, not my scores. She doesn't mind about my scores at school. My day continues with lunch at 11.30 a.m. Then at 11.45 a.m, I have a shower and prepare the clothes and the books to be ready to go to school. My school is not the same as other schools. The seventh and eighth-graders have classes at 12.45 a.m because my school doesn't have enough classes so the school time is divided into two times-morning and afternoon. Then after 5 classes, I go home at 5 o'clock and then I start retelling my mother about my studies at school and shows her my marks. Then I have a shower again. My mother never lets me stay any longer if I don't wash my body again because she really knows that my sweat is very sour. Then I have dinner at 6 p.m. I watch TV after that until 6.30 p.m. Next, I start working with my work at school.

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