the area of circle o is added to its diameter . if the circumference of circle o is then subtracted from this total , the result is 4 . what is the area of circle o ?
area + diameter - circumference = 4 pi * r ^ 2 + 2 r = 4 + 2 pi * r isolate r and get r ( pi * r + 2 ) = 4 + 2 pi * r r = ( 4 + 2 pi * r ) / ( pi * r + 2 ) = > 2 ( 2 + pi * r ) / ( pi * r + 2 ) r = 2 area = pi * r ^ 2 = > pi * 4 e
multiply(4, const_pi)