3.
var x:array[1..10] of real;
k:integer;
begin
write('x[1] = '); readln(x[1]);
write('x[2] = '); readln(x[2]);
for k:=3 to 10 do
  x[k]:=sin(x[k-1]-x[k-2])/cos(x[k-1]-x[k-2])+sqrt(abs(sin(x[k-1])))
;for k:=1 to 10 do write(x[k]:5:2);
writeln;
end.

Пример:
x[1] = 1
x[2] = 1
1.00 1.00 0.92 0.81 0.74 0.75 0.84 0.95 1.01 0.98

4.
const n=10;
var x:array[1..n] of real;
i:integer; s,p:real;
begin
Randomize;
writeln('Массив x:');
for i:=1 to n do
 begin
 x[i]:=3*random;
 write(x[i]:6:2);
 end;
writeln;
p:=1;
for i:=1 to n do p:=p*x[i];
writeln('p = ',p);
s:=1+exp(p);
writeln('S = ',s);
end.

Пример:
Массив x:
  1.98  1.38  2.96  2.14  1.64  1.94  2.32  2.74  0.00  2.10
p = 0.371053196230522
S = 2.449260166514