. , ( ) .
f(x), a b N . Δx Δx=(b-a)/N.
, , , , . ( ) , , . sin x .
1. .
Δx :
, xi .
z:=0;
dx:=(b-a)/N;
x:=a+dx/2;//
for i:=1 to N do
begin
z:=z+Sin(x);
x:=x+dx
end;
z:=z*dx;
2. .
.
z:=(Sin(a)+Sin(b))/2;
dx:=(b-a)/N;
x:=a+dx;
for i:=1 to N-1 do
begin
z:=z+Sin(x);
x:=x+dx
end;
z:=z*dx;
3. ().
, N 2 , , 2
.
.
ReadLn(a,b,N);
Integ:=Sin(a);
dx:=(b-a)/N;
for i:=1 to N div 2 do
begin
x:=a+2*i*dx;
Integ:=Integ+2*Sin(x)+4*Sin(x-dx);
end;
Integ:=(Integ-Sin(b))*dx/3;
WriteLn(Integ:10:5);
Itoch:=-(Cos(b)-Cos(a));
WriteLn(Itoch:10:5);
ReadLn;