main.c

#include <stdio.h>

int main() {

    double A, B, C, temp;

    scanf("%lf %lf %lf", &A, &B, &C);

    if (A < B) {
        temp = A;
        A = B;
        B = temp;
    }

    if (B < C) {
        temp = B;
        B = C;
        C = temp;
    }

    if (A < B) {
        temp = A;
        A = B;
        B = temp;
    }

    if (A >= B + C)
        printf("NAO FORMA TRIANGULO\n");

    else if (A * A == B * B + C * C)
        printf("TRIANGULO RETANGULO\n");

    else if (A * A > B * B + C * C)
        printf("TRIANGULO OBTUSANGULO\n");

    else if (A * A < B * B + C * C)
        printf("TRIANGULO ACUTANGULO\n");

    if (A == B && B == C)
        printf("TRIANGULO EQUILATERO\n");

    else if (A == B || B == C)
        printf("TRIANGULO ISOSCELES\n");

    return 0;
}