Giải hộ mk vs ah
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12 tháng 1 2020
GT:AH vuông BC
AD=AB
DI vuông AH
KL:BH=ID
Bài làm
Ta có:
\(\widehat{A1}=\widehat{A2}\)(đối đỉnh)(1)
\(AB=AD\)(GT)(2)
mà\(\widehat{B}=180^0-90^0-\widehat{A1}\)
\(\widehat{D}=180^0-90^0-\widehat{A2}\)
và\(\widehat{A1}=\widehat{A2}\)
=>\(\widehat{B}=\widehat{D}\)(3)
Từ (1),(2),(3) suy ra:\(\Delta\)ABH=\(\Delta\)ADI(g-c-g)
=>BH=ID(hai cạnh tương ứng)
Vậy BH=ID
20 tháng 9 2015
Hình vẽ : tự vẽ nha
Sabc = \(\frac{1}{2}AH.BC=\frac{1}{2}BK.AC\)
=> \(AH.BC=AC.BK\)
=> \(\frac{AH}{BK}=\frac{AC}{BC}=\frac{15.6}{12}=\frac{13}{10}\)
=> \(\frac{AC}{13}=\frac{BC}{10}=t\)
=> \(AC=13t;BC=10t\)
Tam giác ABC cân có AH là đg cao => AH là t tuyến => BH = HC = 1/2 BC = 1/2.10t = 5t
TAm giác AHC vuông tại H , theo py ta go :
\(AC^2-HC^2=15.6^2\)
=> \(169t^2-25t^2=15.6^2\)
tính ra t thay vào tìm ra BC
20 tháng 9 2015
2SABC = AH.BC = AC.BK
ð 15,6BC = 12AC
ð BC = 12/15,6AC
ð CH = 6/15,6AC
ð AH2 = AC2 – HC2 = 144/169AC2
ð AH = 12/13 AC
ð 15,6 = 12/13AC
ð AC = 16,9
ð BC = 12/15,6 AC = 13
VA
1
DT
Đỗ Thanh Hải
CTVVIP
6 tháng 6 2021
III
1 appreciated
2 worried
3 tense
4 confident
5 delighted
6 frustrated
7 calm
8 relaxed
9 self-disciplined
10 depressed
V
1 had resolved
2 has taken
3 Did you say
4 not to take
5 wanted
6 is being repaired
7 taking
8 to think
9 had worked
10 was washing - dropped
11 will find
12 faces
13 turned
14 to give
15 will empathise
3 tháng 9 2021
Đặt \(A=\dfrac{1}{\sqrt[3]{a+7b}}+\dfrac{1}{\sqrt[3]{b+7c}}+\dfrac{1}{\sqrt[3]{c+7a}}\)
\(A=\dfrac{\sqrt[3]{64}}{\sqrt[3]{8.8\left(a+7b\right)}}+\dfrac{\sqrt[3]{64}}{\sqrt[3]{8.8\left(b+7c\right)}}+\dfrac{\sqrt[3]{64}}{\sqrt[3]{8.8\left(c+7a\right)}}\)
\(\ge\dfrac{4}{\dfrac{8+8+a+7b}{3}}+\dfrac{4}{\dfrac{8+8+b+7c}{3}}+\dfrac{4}{\dfrac{8+8+c+7a}{3}}\ge\dfrac{\left(2+2+2\right)^2}{\dfrac{8+8+a+7b+8+8+b+7c+8+8+c+7a}{3}}\)
\(=\dfrac{36.3}{8\left(a+b+c\right)+48}=\dfrac{3}{2}\)
Vậy \(A_{min}=\dfrac{3}{2}\Leftrightarrow a=b=c=1\)
DT
Đỗ Thanh Hải
CTVVIP
22 tháng 5 2021
I
1 D
2 C
3 A
II
4 C
5 B
Part B
6 A
7 D
8 B
9 C
10 A
11 C
12 C
13 B
14 C
15 D
16 A
17 B
18 D
19 C
20 A
DT
Đỗ Thanh Hải
CTVVIP
22 tháng 5 2021
1 A
2 C
3 D
4 C
5 D
6 D
7 A
8 D
9 B
10 A
11 B
12 A
13 A
14 C
15 C
16 A
17 A
18 B
19 A
20 D
1 Your sister is interested in doing DIY in her free time, isn't she?
2 Unless that girl study harder, she will fail the exam
3 My father has given up smoking since last year
4 Mary wanted to know what Peter would give his brother on his birthday the day after
1. Your sister is interested in doing DIY in her free time, isn't she?
2. Unless that girl studies harder, she'll fail the exam.
3. My father has given up smoking since last year.
4. Mary wanted to know what Peter would give his brother on his birthday the next day.