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Explanation

Let the coordinates of `A` be `(0,alpha)`. Since, the sides `AB` and `AD` are parallel to the lines `y=x+2` and `y=7x+3`, respectively.

`:.` The diagonal `AC` is parallel to the bisector of the angle between these two lines. The equation of the bisectors are given by
`(x-y+2)/(sqrt(2))=+-(7x-y+3)/(sqrt(50))`
`implies 5(x-y+2)=+-(7x-y+3)`
`implies2x+4y-7=0` and `12x-6y+13=0`
Thus, the diagonals of the rhombus are parallel to the lines `2x+4y-7=0` and `12x-6y+13=0`
`:.` Slope of `AE=-(2)/(4)` or `(12)/(6)`
`implies(2-alpha)/(1-0)=-(1)/(2)` or `(2-alpha)/(1-0)=2`
`implies alpha=(5)/(2)` or `alpha=0`
Hence, the coordinates are `(0,5//2)` or `(0,0)`.