Câu 3

uses crt;

var a,b,c,s,cv:real;

begin

clrscr;

write('Nhap canh a: ');readln(a);

write('Nhap canh b: ');readln(b);

write('Nhap canh c: ');readln(c);

if (a+b>c) and (b+c>a) and(a+c>b) 

then begin

writeln('Day la ba canh tam giac');

cv:=a+b+c;

s:=(sqrt((a+b+c)*(a+b-c)*(b+c-a)*(a+c-b)))/4;

writeln('Chu vi: ',cv);

writeln('Dien tich: ',s);

end else writeln('Day khong phai ba canh tam giac');

readln

end.

Câu 4

uses crt;

var tam,m,n: integer;

begin

clrscr;

write('nhap m= '); readln(m);

write('nhap n= '); readln(n);

tam:=m;

m:=n;

n:=tam;

writeln('Sau khi doi: ',m,', ',n);

readln

end.

Câu 5

Uses CRT;

Var a,b,c,D,x,x1,x2: real;

Begin 

Clrscr;  

Write('Nhap he so a=');readln(a);  

Write('Nhap he so b='); readln(b);  

Write('Nhap he so c='); readln(c);  

If a=0 then    

If b=0 then      

If c=0 then        

Writeln('Phuong trinh co vo so nghiem')      

Else Writeln('Phuong trinh vo nghiem')    

Else Writeln('Phuong trinh co mot nghiem: x=',-c/b: 4: 2)  

Else    

Begin      

D:=b*b-4*a*c;     

If D=0 then Writeln('Phuong trinh co nghiem kep: x=',-b/(2*a): 4: 2)      

Else If D<0 then Writeln('Phuong trinh vo nghiem')        

Else Begin x1:=(-b-sqrt(D))/(2*a);             

x2:=(-b+sqrt(D))/(2*a);             

Writeln('Phuong trinh co 2 nghiem la x1= ',x1:4:2 ,' va x2= ',x2:4:2);            

End;     

End;

Readln

End.

3.

uses crt;
var a,b,c:longint; p:real;
begin
clrscr;
   write('a,b,c=');readln(a,b,c);
   if(a+b>c)and(a+c>b)and(b+c>a) then
      begin
         writeln('Yes');
         writeln('Chu vi: ',a+b+c);
         p:=(a+b+c)/2;
         writeln('Dien tich: ',sqrt(p*(p-a)*(p-b)*(p-c)));
      end else writeln('No');
readln
end.

4.

uses crt;
var m,n,t:longint; p:real;
begin
clrscr;
   write('m,n=');readln(m,n);
   t:=m; m:=n; n:=t;
   writeln('m=',m,'; n=',n);
readln
end.