On the line joining (1, 0) and (3, 0) an equilateral triangle is drawn, having its vertex in the first quadrant. Find the equation to the circles described on its sides as diameter
a) x² +y² −2x−4y=0
b) x² +y² −4x−2y=0
c) x² +y² −2x−2y=0
d) x² +y² −6x−6y=0