Image is answer

A  =  (-2,1)   B  =  (4,1)

The side length of AB  = 6

And C  will have an x coordinate value  of  (4 - 2) / 2  =  2/2   =  1

So...C  = (1, y)

So....we can find the possible y values  of C  by setting the distance between A and C = 6...so we have

sqrt [ (-2 - 1)^2 + ( y - 1)^2 ]  =  6          square both sides

(-2 - 1)^2 + (y - 1)^2   =  36       simplify

(-3)^2 + (y - 1)^2  =  36

9 + (y - 1)^2  = 36   subtract 9 from both sides

(y - 1)^2 = 27      take both roots

y -  1  = ±√27

y =  ±3√3 + 1      =   -4.2   and  6.2

So...the possible coordinates for C are

(1, -4.2)     and   (1, 6.2)