\(\frac{1+cosx-sinx}{1-cosx-sinx}=\frac{1+2cos^2\frac{x}{2}-1-2sin\frac{x}{2}.cos\frac{x}{2}}{1-1+2sin^2\frac{x}{2}-2sin\frac{x}{2}.cos\frac{x}{2}}=\frac{2cos^2\frac{x}{2}-2sin\frac{x}{2}.cos\frac{x}{2}}{2sin^2\frac{x}{2}-2sin\frac{x}{2}.cos\frac{x}{2}}\)

\(=\frac{-2cos\frac{x}{2}\left(sin\frac{x}{2}-cos\frac{x}{2}\right)}{2sin\frac{x}{2}\left(sin\frac{x}{2}-cos\frac{x}{2}\right)}=\frac{-cos\frac{x}{2}}{sin\frac{x}{2}}=-cot\frac{x}{2}\)

Program HOC24;

const fi='dodai.inp';

fo='xau.out';

var s: array[1..5] of string;

i: integer;

f: text;

procedure ip;

begin

assign(f,fi);

reset(f);

for i:=1 to 5 do readln(f,s[i]);

close(f);

end;

procedure out;

begin

assign(f,fo);

rewrite(f);

for i:=1 to 5 do writeln(f,length(s[i]));

close(f);

end;

begin

ip;

out;

end.

seven
twenty
forty
ten
thirty
còn lại chịu
 

câu trả lời của các bạn ko đc lay ví dụ;

-seve,seventy

10 từ mà 

Bạn check cho mik X + E + D -> U + E 

1. C

2. D

3. C

4. D

5. D

6. B

7. D

8. B

9. C

bằng ?

và bằng 

A+S+D+F+G+H+J+K+L+M+NB++V+C+X+Z+Q+W+E+R+T+Y+U+I+O+P-A-S-D-F-G-H-J-K-L-MN-B-V-C-XZ-Q-W-E-R--T-Y-U-I-O-P/AS/D/F/G/H/J/K/L/M/N/B/V/C/X/Z/Q//W/E/R/T/Y/U/I/O/P/

ko bằng gì cả

Bài 1:

const fi='mangmin.inp';

fo='mangmin.out';

var f1,f2:text;

a,vt:array[1..100]of integer;

n,i,dem:integer;

begin

assign(f1,fi); reset(f1);

assign(f2,fo); rewrite(f2);

readln(f1,n);

for i:=1 to n do

read(f1,a[i]);

min:=a[1];

for i:=1 to n do

if min>a[i] then min:=a[i];

dem:=0;

for i:=1 to n do

if min=a[i] then

begin

inc(dem);

vt[dem]:=i;

end;

writeln(f2,'Gia tri nho nhat la: ',min);

writeln(f2,'Vi tri cua gia tri nho nhat la: ');

for i:=1 to dem do

write(f2,vt[i]:4);

close(f1);

close(f2);

end.

Bài 2:

const fi='mangchan.inp';

fo='mangchan.out';

var f1,f2:text;

a:array[1..100]of integer;

n,i,t:integer;

begin

assign(f1,fi); reset(f1);

assign(f2,fo); rewrite(f2);

readln(f1,n);

for i:=1 to n do

read(f1,a[i]);

t:=0;

for i:=1 to n do

if a[i] mod 2=0 then t:=t+a[i];

writeln(f2,t);

close(f1);

close(f2);

end.

Bài 3:

const fi='tachxau.inp';
fo='tachxau.out';
var f1,f2:text;
s,s1,s2,s3,s4:string;
i,d:integer;
j,k,l:char;
begin
assign(f1,fi); reset(f1);
assign(f2,fo); rewrite(f2);
readln(f1,s);
d:=length(s);
s1:='';
for i:=1 to d do
if s[i] in ['0'..'9'] then s1:=s1+s[i];
writeln(f2,'Xau S1 la: ',s1);
s2:='';
for i:=1 to d do
if s[i] in ['a'..'z'] then s2:=s2+s[i];
writeln(f2,'Xau S2 la: ',s2);
s3:='';
for i:=1 to d do
if s[i] in ['A'..'Z'] then s3:=s3+s[i];
writeln(f2,'Xau S3 la: ',s3);
close(f1);
close(f2);
end.

Bài 4:

const fi='demtu.inp';
fo='demtu.out';
var s:string;
i,d,dem:integer;
kt:boolean;
f1,f2:text;
begin
assign(f1,fi); reset(f1);
assign(f2,fo); rewrite(f2);
readln(f1,s);
d:=length(s);
i:=0;
while i<=d do
begin
inc(i);
if ((i=1) and (s[i]=' ')) then
repeat
kt:=false;
if (s[i]=' ') then
begin
delete(s,i,1);
d:=length(s);
end
else kt:=true;
until (kt=true) or (i+1>d)
else repeat
kt:=false;
if (s[i]=' ') and (s[i+1]=' ') then
begin
delete(s,i,1);
d:=length(s);
end
else kt:=true;
until (kt=true) or (i+1>d);
d:=length(s);
end;
while s[d]=' ' do
begin
delete(s,d,1);
d:=length(s);
end;
dem:=0;
for i:=1 to d do
if s[i]=' ' then dem:=dem+1;
writeln(f2,dem+1);
close(f1);
close(f2);
end.

1:

uses crt;

var st1,st2:string;

begin

clrscr;

write('Nhap xau thu nhat:'); readln(st1);

write('Nhap xau thu hai:'); readln(st2);

if length(st1)>length(st2) then writeln(st2)

else if length(st1)<length(st2) then writeln(st1)

else writeln('Hai xau co do dai bang nhau');

readln;

end.

2:

uses crt;

var st:string;

i,d,dem:integer;

begin

clrscr;

write('Nhap xau:'); readln(st);

d:=length(st);

dem:=0;

for i:=1 to d do

if st[i]=' ' then inc(dem);

writeln('So luong dau cach trong xau ',st,' la: ',dem);

readln;

end.