Find the asbolute max or min on set D

f(x,y)=xy^2

D={(x,y)|x>=0,y>=0,x^2+y^2<=3}

so fx=y^2 and fy=2xy our criticl point is at (0,0) which correspponds to f(0,0)=0 now my problem is how do i get the other points to check am i right in saying they are

(0,3),(3,3),(3,0)? thanks for help!