E2268 Call to undefined function 'sqr'

void __fastcall TForm1::Button1Click(TObject *Sender)
{
 int i,ii;
 double a,b,d,r,rr;
 
 ii=-1;
 d=1.000;
 
 for(int i=-3;i<3;i++)
 {
  a=d;
  b=fabs(i) * d;
  ii++;
  rr=sqr(a)+ sqr(b);
  r=sqrt(rr);
  StringGrid1->Cells[ii+1][1]=r;
 }
}

pow(a,2)+pow(b,2);

StringGrid1->RowCount=сколько надо

StringGrid1->RowCount++;

//---------------------------------------------------------------------------
 
#include <vcl.h>
#pragma hdrstop
 
#include "Writer.h"
#include "math.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
    : TForm(Owner)
{
 StringGrid1->Cells[1][0]="       i";
 StringGrid1->Cells[2][0]="       r";
 
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Button1Click(TObject *Sender)
{
 int i,ii;
 double a,b,d,r;
 
 ii=-1;
 d = Edit1->Text.ToDouble();
 d = StrToFloat(Edit1->Text);
 
 for(int i=-3;i<3;i++)
 {
  a=d;
  b=fabs(i) * d;
  ii++;
  r=pow(a,2)+pow(b,2);
  r=sqrt(r);
  StringGrid1->Cells[2][ii+1]=r;
  StringGrid1->Cells[1][ii+1]=i;
  if(StringGrid1->RowCount<=i){
  StringGrid1->RowCount++;
    }
 }
}
//---------------------------------------------------------------------------

rr=a*a+ b*b;

__fastcall TForm1::TForm1(TComponent* Owner)
  : TForm(Owner) 
{
  StringGrid1->Cells[1][0]="       i";
  StringGrid1->Cells[2][0]="       r";   
}