ПОМОГИТЕ НАЙТИ ОШИБКУ!!!!!!!!!!!!!! Паскаль
program z232;
var
operation:byte;
a,b:real;
function summa(x,y:real):real;
begin
summa:=a+b
end;
function raznost(a,b:real): real;
begin
raznost:=a-b
end;
function delenie(a,b: real): real;
begin
delenie:=a/b
end;
function proizved(a,b:real): real;
begin
proizved:=a*b
end;
function sqrt(a,b:real): real;
sqrt:=sqrt(a);
sqrt:=sqrt(b);
end;
function abs(a.b:real): real;
abs:=abs(a);
abs:=abs(b):
end;
function sin(a.b:real): real;
sin:=sin(a);
sin:=sin(b);
end;
function cos(a.b:real): real;
cos:=cos(a);
cos:=cos(b);
end;
function tan(a.b:real): real;
tan:=tan(a);
tan:=tan(b);
end;
function sqr(a.b:real): real;
sqr:=sqr(a);
sqr:-sqr(b);
end;
begin
writeln('a');
read(a);
writeln('b');
read(b);
writeln('1 - сложить');
writeln('2 - вычесть');
writeln('3 - разделить');
writeln('4 - умножить');
writeln('5 - корень');
writeln('6 - модуль');
writeln('7 - синус');
writeln('8 - косинус');
writeln('9 - тангенс');
writeln('10 - квадрат');
read(operation);
case operation of
1: writeln(summa(a.b));
2: writeln(raznost(a.b));
3: writeln(delenie(a.b));
4: writeln(proizved(a.b));
5: writeln(sqrt(a.b));
6: writeln(abs(a.b));
7: writeln (sin(a.b));
8: writeln(cos(a.b));
9: writeln(tan(a.b));
10: writeln(sqr(a.b));
end;
end.

program z232;var  operation: byte;  a, b: real;function summa(x, y: real): real;begin  summa := a + bend;function raznost(a, b: real): real;begin  raznost := a - bend;function delenie(a, b: real): real;begin  delenie := a / bend;function proizved(a, b: real): real;begin  proizved := a * bend;function sqrt(a, b: real): real;begin  sqrt := sqrt(a);  sqrt := sqrt(b);end;function abs(a, b: real): real;begin  abs := abs(a);  abs := abs(b);end;function sin(a, b: real): real;begin  sin := sin(a);  sin := sin(b);end;function cos(a, b: real): real;begin  cos := cos(a);  cos := cos(b);end;function tan(a, b: real): real;begin  tan := tan(a);  tan := tan(b);end;function sqr(a, b: real): real;begin  sqr := sqr(a);  sqr := sqr(b);end;begin  writeln('a');  read(a);  writeln('b');  read(b);  writeln('1 - сложить');  writeln('2 - вычесть');  writeln('3 - разделить');  writeln('4 - умножить');  writeln('5 - корень');  writeln('6 - модуль');  writeln('7 - синус');  writeln('8 - косинус');  writeln('9 - тангенс');  writeln('10 - квадрат');  read(operation);  case operation of    1: writeln(summa(a, b));    2: writeln(raznost(a, b));    3: writeln(delenie(a, b));    4: writeln(proizved(a, b));    5: writeln(sqrt(a, b));    6: writeln(abs(a, b));    7: writeln(sin(a, b));    8: writeln(cos(a, b));    9: writeln(tan(a, b));    10: writeln(sqr(a, b));  end;end.