y = sqrt (r^2 – x^2)

y = | sqrt (r^2 – x^2) |

the absolute value will get rid of the bottom half of the circle.

undertaking-free! merely remedy for ‘y’ ! in case you like an illustration… (x – 6)^2 + (y + a million)^2 = a million…………………….unique (y + a million)^2 = a million – (x – 6)^2……………………..Subtract (x-6)^2 y + a million = ±sqrt( a million – (x – 6)^2 )………………….sq. root y = ±sqrt( a million – (x – 6)^2 ) – a million…………………..Subtract a million for terribly final answer So the equations could be y = sqrt( a million – (x – 6)^2 ) – a million and y = a million – sqrt( a million – (x – 6)^2 ) . The effective one is the main appropriate 0.5. The damaging one is the backside 0.5. that is that straightforward!