import matplotlib.pyplot as plt
def triangle(A,B,C):
    sommet1=A
    sommet2=B
    sommet3=C
    x=[sommet1[0],sommet2[0],sommet3[0],sommet1[0]]
    y=[sommet1[1],sommet2[1],sommet3[1],sommet1[1]]
    plt.plot(x,y,"r")