C

hello brothers! I have not found the section of programming on this forum, pls tell me where i was wrong

main()
{
float a, b, h, Q;
const float pi = 3.1415926535;
const float e = 0.00001;
printf ("Vvedite a, Q\n");
scanf ("%f %f", &a, &Q);
if (a>=0 && a<=pi)
{
do
{
b=a-((a-sin(a)-2*pi*Q)/1-cos(a));
}
while (fabs(b-a)<e);
h=1*(1-cos(b/2));
printf ("h=%f \n", h);
}
else
{
printf("no \n");
}
printf("press any key for exit \n");
getch();
}

i'm noob sorry

const float pi = 3.1415926535;
const float e = 0.00001;

Hey guys, how do I math.h?