Cau 1:
uses crt;
var s, a, b, h: real;
begin
clrscr; 
 write('nhap a, b, h: '); readln(a,b,h);
  s:=h/2*(a+b);
 writeln('dien tich: ',s:6:2);
readln;
end.
Cau 2:
uses crt;
var a, b: real;
begin
clrscr;
 write('nhap a, b: '); readln(a,b);
   if (a=0) then
 if (b=0) then
  writeln('ptrinh vo so nghiem') else
 writeln('ptrinh vo nghiem') else
    writeln('ptrinh co nghiem x=',-b/a:6:2);
readln;
end.
Cau 3:
uses crt;
var a, b, c: real;
begin
clrscr;
 write('nhap a, b, c: '); readln(a,b,c);
   if (a<b+c) and (b<a+c) and (c<b+a) 
 then writeln('day la so do 3 canh tam giac')
  else writeln('day khong phai so do 3 canh tam giac');
readln;
end.
Cau 4:
uses crt;
var a, b, c, max: integer;
begin
clrscr;
 write('nhap a: '); readln(a);
   max:=a;
 write('nhap b: '); readln(b);
  if (b>max) then max:=b;
 write('nhap c: '); readln(c);
  if (c>max) then max:=c;
readln;
end.
Cau 5:
uses crt;
var a, b, c: real;
begin
clrscr;
 write('nhap a, b, c: '); readln(a,b,c);
  if (sqr(a)=sqr(b)+sqr(c)) then
 writeln('day la tam giac vuong, canh huyen: ',a) else
  if (sqr(b)=sqr(a)+sqr(c)) then
 writeln('day la tam giac buong, canh huyen: ',b) else
  if (sqr(c)=sqr(a)+sqr(b)) then
 writeln('day la tam giac vuong, canh huyen: ',c) else
 writeln('day khong phai tam giac vuong');
readln;
end.
Cau 6:
uses crt;
var a: real;
begin
 write('nhap so thuc a: '); readln(a);
  if (a<0) then writeln(a,' la so am) else
 if (a=0) then writeln(a,' la so 0') else
  if (a>0) then writeln(a,' la so duong');
readln;
end.

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