Given, M⇒x2+y2=1, its centre O1≡(0,0) N⇒x2+y2−2x=0,‌ its centre ‌O2≡(1,0) 0⇒x2+y2−2x−2y+1=0,‌ its centre ‌ O3≡(1,1) P⇒x2+y2−2y=0‌, its centre ‌O4≡(0,1) We see that,
O1O2=O2O3=O3O4=O4O1‌ and ‌O1O3=O2O4 Hence, O1O2O3O4 form a square.