Program for calculating the side and angles of a triangle

//---------------------------------------------------------------------------

#include <vcl.h>
#pragma hdrstop

#include "Unit4.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
: TForm(Owner)
{
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Button1Click(TObject *Sender)
{
float a, c, h;
float b, b1, b2;
double A, B, C;
a=StrToFloat(Edit1->Text);
c=StrToFloat(Edit2->Text);
h=StrToFloat(Edit3->Text);
b1=sqrt(a*a-h*h);
b2=sqrt(c*c-h*h);
b=b1+b2;
A=acos((a*a+b*b-c*c)/(2*a*b));
B=acos((a*a+c*c-b*b)/(2*a*c));
C=acos((b*b+c*c-a*a)/(2*b*c));
Edit4->Text = FloatToStr(b);
Edit5->Text = FloatToStr(B);
Edit6->Text = FloatToStr(C);
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Button2Click(TObject *Sender)
{
Form1-> Close();
}
//---------------------------------------------------------------------------

Code

//---------------------------------------------------------------------------



#include <vcl.h>

#pragma hdrstop



#include "Unit4.h"

//---------------------------------------------------------------------------

#pragma package(smart_init)

#pragma resource "*.dfm"

TForm1 *Form1;

//---------------------------------------------------------------------------

__fastcall TForm1::TForm1(TComponent* Owner)

    : TForm(Owner)

{

}

//---------------------------------------------------------------------------

void __fastcall TForm1::Button1Click(TObject *Sender)

{

float a, c, h;

float b, b1, b2;

double A, B, C;

a=StrToFloat(Edit1->Text);

c=StrToFloat(Edit2->Text);

h=StrToFloat(Edit3->Text);

b1=sqrt(a*a-h*h);

b2=sqrt(c*c-h*h);

b=b1+b2;

A=acos((a*a+b*b-c*c)/(2*a*b));

B=acos((a*a+c*c-b*b)/(2*a*c));

C=acos((b*b+c*c-a*a)/(2*b*c));

Edit4->Text = FloatToStr(b);

Edit5->Text = FloatToStr(B);

Edit6->Text = FloatToStr(C);

}

//---------------------------------------------------------------------------

void __fastcall TForm1::Button2Click(TObject *Sender)

{

Form1-> Close();

}

//---------------------------------------------------------------------------

Программа работает, но при вводе чисел выдаёт "Invalid floating point operation". В чём может быть проблема и где ошибка? Подскажите пожалуйста.