How do you find the equation of the circle with center (1,2) and radius 3?

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Answer 1 · 2016-11-10T09:05:44

#x^2+y^2-2x-4y-4=0#

# centre(1,2), radius 3#

eqn circle centre# (a,b)# radius # r#

#(x-a)^2+(y-b)^2=r^2#

#(x-1)^2+(y-2)^2=3^2#

multiplying out

#x^2-2x+1+y^2-4y+4=9#

tidying up

#x^2+y^2-2x-4y-4=0#