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Between August and November 1888, the Whitechapel area of London was the scene of five brutal murders. He was rightly called Jack the Ripper. The ripper was an infamous serial killer. He was the first serial killer to do so in a largely populated area, although it seemed he had no malice for other people. The ripper also had no accomplices and accessories to the crime. Another fact was that he escaped with no charges. All the women murdered were prostitutes, and all except for one (Elizabeth Stride) were horribly mutilated.
His method of attack was to let these prostitutes ‘seduce’ him into using them for their services, which at that time he would strangle them, making them unconscious and killing them, this was done by stalking his victims. This was no motive in his killing either. Oddly enough, it is shown that Jack the Ripper that this murderer was nice to his victims in certain ways.
The first murder, of Mary Ann Nicholls, took place on 31 August. Her throat was cut and her abdomen was cut open brutally, it showed the intestines. She was found by Mr. Llewellyn.
Annie Chapman was killed on 8 September. Her throat was cut and was very maimed. The abdomen was cut open and her intestines were placed on her shoulders.
Elizabeth Stride was murdered on 30 September. Her throat was cut, but she wasn’t maimed. She was found by Mr. Phillips and Mr. Blackwell.
Catherine Eddoweson was also murdered on 30 September. Her throat was cut, her abdomen was cut open and the intestines were placed on her right shoulder. She had a lot of injuries in her face and her left kidney removed. Pieces of Eddowes apron were found in the doorway of a building in Goulston Street. Above her was written a message with chalk: ‘ The juwes are the men that will not be blamed for nothing’.
Mary Jane Kelly was killed on 9 November. She was the youngest and most comfortable of Jack’s victims and she was the most and badly maimed. Many think that she was the only intentional victim. She was murdered in her own room and her heart was missing.
There had been much speculation as to the identity of the killer. It has been suggested that he or she was a doctor or butcher, based on the evidence of weapons and the mutilations that occurred, which showed a knowledge of human anatomy.
Violence to prostitutes wasn’t uncommon and there were many instances of women being brutalised, but the nature of these murders strongly suggests a single perpetrator.
Jack the Ripper was never caught and he is not thought to have killed again after November 1888.
a)Theo hệ quả định lý Ta let có:
Xét tam giác FMC có :
AB // CD => AB // MC nên BF/FM=AB/CM(1)
Xét tam giác EDM có :
AB // DM => AE/EM=AB/DM(2)
Mà M là trung điểm DC => DM = MC
=> AB/DM=AB/MC(3)
Từ (1) (2) (3) => AE/EM=BF/FM
Xét tam giác MBA có : AE/EM=BF/FM=> EF // AB
b)Xét tam giác EDM có AB // DM => ME/AM=DM/AB(4)
Do EF//AB => EF/AB=ME/AM(5)
Từ (4) và (5) => DM/AB=EF/AB⇒EF=DM=12/2=6cm
Gọi số học sinh của từng khối lần luotj là: a, b, c, d (a, b, c, d ∈ N*)
Theo bài ra, ta có: \(\frac{a}{9}=\frac{b}{8}=\frac{c}{7}=\frac{d}{6}\) và a+b+c+d=1050
Theo tính chất dãy tỉ số bằng nhau, ta có:
\(\frac{a}{9}\) \(=\frac{b}{8}=\frac{c}{7}=\frac{d}{6}=\frac{a+b+c+d}{9+8+7+6}=\frac{1050}{30}=35\)
_\(\frac{a}{9}\)= 35 ⇒ 315
_\(\frac{b}{8}\) = 35 ⇒ 280
_ \(\frac{c}{7}\) = 35 ⇒245
_\(\frac{d}{6}\) = 35 ⇒210
Vậy số học sinh của các khối là: khối 6: 315 hs
Khối 7: 280 hs
Koois 8: 245 hs
Khối 9: 210 hs
học tốt
Trả lời:
+ Gọi số học sinh mỗi khối lần lượt là a, b, c, d (học sinh)
Đk: \(a,b,c,d\inℕ^∗\)
+ Vì một trường THCS có 1050 học sinh.
\(\Rightarrow a+b+c+d=1050\)
+ Vì số học sinh của bốn khối 6, 7, 8, 9 lần lượt tỉ lệ với 9, 8, 7, 6
\(\Rightarrow\frac{a}{9}=\frac{b}{8}=\frac{c}{7}=\frac{d}{6}\)
\(\Rightarrow\frac{a}{9}=\frac{b}{8}=\frac{c}{7}=\frac{d}{6}=\frac{a+b+c+d}{9+8+7+6}\)\(=\frac{1050}{30}=35\)(Tính chất dãy tỉ số bằng nhau và a + b + c + d = 1050)
\(\Rightarrow\)\(a=35.9=315\)
\(b=35.8=280\)(Thỏa mãn Đk:\(a,b,c,d\inℕ^∗\))
\(c=35.7=245\)
\(d=35.6=210\)
Vậy số học sinh mỗi khối 6, 7, 8, 9 lần lượt là 315 học sinh, 280 học sinh , 245 học sinh, 210 học sinh.
Hok tốt!
Good girl
Bài 2: Gọi độ dài 3 cạnh của tam giác là a,b,c ( a,b,c>0)
chu vi của tam giác là 22 nên a+b+c = 22
vì a, b, c tỉ lệ với 2; 4; 5 nên a/2=b/4=c/5
\(\frac{a}{2}=\frac{b}{4}=\frac{c}{5}=\frac{a+b+c}{2+4+5}=\frac{22}{11}=2\)
suy ra a= 4; b = 8; c = 10
Bài 3: \(x:y:z=2:4:5\Rightarrow\frac{x}{2}=\frac{y}{4}=\frac{z}{5}=\frac{x+y+z}{2+4+5}=\frac{22}{11}=2\)
suy ra x= 4, y=8, z=10
