how to label figure with vertex point in matlab

I have a ploygon with four vertex points , how can I label those vertex point as 'A','B','C','D'.

Answer 1

[KSSV]

A = rand(1,2) ;
B = rand(1,2) ;
C = rand(1,2) ;
P = [A;B;C;A] ; 
label = {'A'; 'B' ; 'C'} ;
plot(P(:,1),P(:,2),'.-r')
text(P(1:3,1),P(1:3,2),label)