For the four circles M, N, O and P, following four equations are given: Circle M: x^2+y^2=1 Circle N: x^2+y^2-2 x=0 Circle O: x^2+y^2-2 x-2 y+1=0…

For the four circles $\displaystyle \mathrm{M}, \mathrm{N}, \mathrm{O}$ and P , following four equations are given : Circle M : $\displaystyle x^2+y^2=1$ Circle $\displaystyle \mathrm{N}: x^2+y^2-2 x=0$ Circle $\displaystyle \mathrm{O}: x^2+y^2-2 x-2 y+1=0$ Circle P : $\displaystyle x^2+y^2-2 y=0$ If the centre of circle M is joined with centre of the circle N , further centre of circle N is joined with centre of the circle O, centre of circle O is joined with the centre of circle P and lastly, centre of circle P is joined with centre of circle M , then these lines form the sides of a :