Programming

function sqrt not declared

#include <stdio.h> 
#include <math.h>

int main(void) {
    
    float a,b,c;
    
    // Asks user to enter sides
    
    printf("\t\tTriangle detection triangle\n");
    printf("Enter three sides of the triangle: ");
    scanf("%f, %f, %f", &a, &b, &c);
    
    if (a <= 0 || b <= 0 || c <= 0) {
        printf("Invalid input\n");
        return 1;
        }
    else if (a + b > c && a + c > b && b + c > a) {
        printf("Valid entry!\n");
        }
    if ( a != b && a != c && b != a && b != c && c != a) {
        printf("isoscelesm\n");
        }
    else if ( a == b && a == c ) { 
        printf("equilateral\n");
        }
    else if ( b == a && b == c ) {
        printf("equilateral\n");
        }
    else if ( c == a && c == b) {
        printf("equilateral\n");
        }
    else if (c == sqrt (a * a  + b * b)) {
        printf("equilateral\n");
        }
    
    return 0;
}

cc -o myprog  myprog.c -lm

        if((10000000000000001.0-10000000000000000.0) == 1.0)
        {
                printf("equal\n");
        }